JP2003348592A - Image data storage device, encoding device, decoding device, and compression and expansion system - Google Patents

Abstract

(57) [Problem] To provide an image data storage device capable of reducing a storage capacity while suppressing an increase in a processing amount. SOLUTION: A frame to be decoded and a reference frame are stored in an uncompressed form in a frame memory M1,
The reference frame compressed losslessly by the compression circuit A1 is stored in the frame memory M2, and the reference frame compressed lossy by the compression circuits A2 and A3 is stored in the frame memories M3 and M4. The compression ratio of the compression circuit A3 is higher than the compression ratio of the compression circuit A2. A reference frame that is frequently used is stored without being compressed, and is compressed and stored at a higher compression ratio as the frequency of use is reduced. Since the reference frame is stored in an appropriate storage mode in consideration of the frequency of use, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image data storage device for compressing image data and storing the compressed image data in frame units, and a related technique.

[0002]

2. Description of the Related Art International standards such as MPEG-4 and H.264. When encoding moving image data using a moving image compression encoding method such as H.263, compression using temporal correlation between frames is performed in addition to compression using spatial correlation within a frame.

When utilizing the temporal correlation between frames,
The motion compensation is performed with reference to the frame coded immediately before the frame to be coded, and the difference data between the predicted frame obtained by the motion compensation and the frame to be coded is compressed and coded.

Therefore, a moving picture encoding apparatus for compressing moving picture data by the above-mentioned moving picture compression coding method, and a moving picture for decoding moving picture data compressed by the above moving picture compression coding method. In the decoding device, a frame memory for storing a frame to be referred to is required.

In such a moving picture coding apparatus and a moving picture decoding apparatus, a B picture (Bid
directionally predictive-c
In the case of using a frame referred to as “coded picture” that performs motion compensation by predicting from both directions of a front frame and a rear frame, the order of frames differs between input image data and output image data. Therefore, a frame memory for rearrangement is required.

In general, the amount of image data is large, and therefore the capacity of the frame memory is also large. Therefore, various technologies that can reduce the capacity of the frame memory have been proposed.

A conventional decoding device capable of reducing the capacity of a frame memory is disclosed, for example, in Japanese Patent Application Laid-Open No. 9-247673.
Moving image decoding apparatus disclosed in
-261635, a moving picture decoding apparatus disclosed in
and so on.

First, a moving picture decoding apparatus disclosed in Japanese Patent Application Laid-Open No. 9-247773 will be described with reference to the drawings.

FIG. 16 is a block diagram of a conventional moving picture decoding apparatus. As shown in FIG. 16, the conventional video decoding apparatus includes a variable length decoding circuit 900, an inverse quantization circuit 910, an inverse orthogonal transform circuit 920, an adder 930, an image data storage unit 940, and a motion compensation. A circuit 950.

The image data storage section 940 includes a compression circuit 94
1, a frame memory 942, and a decompression circuit 943.

Next, the flow of processing in the conventional moving picture decoding apparatus shown in FIG. 16 will be described. The variable length decoding circuit 900 performs a variable length decoding process on the input encoded video data and outputs the result to the inverse quantization circuit 910.

The inverse quantization circuit 910 performs an inverse quantization process on the input image data, and
20.

When the input image data is image data compressed between frames, the inverse orthogonal transform circuit 920 adds the image data subjected to the inverse orthogonal transform process to the adder 93.
Output to 0.

On the other hand, if the input image data is not image data compressed between frames, the inverse orthogonal transform circuit 9
Reference numeral 20 denotes an external and image data storage unit 94 which converts the image data subjected to the inverse orthogonal transform processing into decoded moving image data.
Output to 0.

The adder 930 includes a motion compensating circuit 95
0 and motion-compensated image data input from 0 and difference data that is image data input from the inverse orthogonal transform circuit 920, and the addition result is output as decoded moving image data to the external and Output to the image data storage unit 940.

The image data storage section 940 stores the image data input from the inverse orthogonal transform circuit 920 and the adder 93.
Image data input from 0 is stored as image data of a reference frame in the decoding process of the next frame. This will be described in detail later.

The motion compensation circuit 950 receives the motion vector decoded and input from the variable length decoding circuit 900 and the image data of the reference frame input from the image data storage unit 940 and performs motion compensation. Output to the adder 930.

Next, the details of the image data storage unit 940 will be described. In the image data storage unit 940, the compression circuit 941 converts the reference frame image data input from the adder 930 and the reference frame input from the inverse orthogonal transform circuit 920 to reduce the storage capacity of the frame memory 942. Compress image data.

The frame memory 942 stores the compressed image data of the reference frame. The expansion circuit 943 is
The frame memory 94 is compressed by the compression means 941.
2, the image data of the reference frame stored in
Output to the motion compensation circuit 950.

Next, a conventional moving picture decoding apparatus disclosed in Japanese Patent Application Laid-Open No. 9-261635 will be briefly described.

This conventional moving picture decoding apparatus includes a data compression circuit for compressing a decoded image and storing the compressed image in a frame memory, and a data decompression circuit for decompressing the data compressed by the data compression circuit.

In this way, the capacity of the frame memory required for storing the reference image and rearranging the decoded image can be reduced.

[0023]

Now, the H.264 standard which aims to enable high-quality moving image communication even in a low bit rate environment at present. An international standard for a moving image compression encoding system called 26L is being formulated.

This H. In the case of H.26L, it has been studied that not only the immediately preceding frame but also one frame can be selected from a plurality of frames and used as a reference frame used for forward prediction.

As described above, in the moving picture coding apparatus or the moving picture decoding apparatus using a plurality of frames as reference frames, the data amount of the reference frame stored in the frame memory 942 of the image data storage unit 940 is further increased. Become.

For this reason, the necessity of reducing the storage capacity of the frame memory 942 of the image data storage unit 940 becomes greater than when one frame is used as a reference frame.

That is, a technique capable of further reducing the storage capacity of the frame memory 942 of the image data storage unit 940 as compared with the conventional moving picture decoding apparatus aimed at reducing the storage capacity of the frame memory of the image data storage unit. Is required.

Further, when a plurality of frames can be used as reference frames, if the plurality of reference frames are uniformly compressed by applying the image data storage unit 940 of the conventional moving picture decoding apparatus, the compression and the The processing amount for decompression increases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image data storage device capable of reducing the storage capacity while suppressing an increase in the processing amount, and its related art.

Another object of the present invention is to provide an image data storage device capable of reducing storage capacity while improving user convenience.

[0031]

In an image data storage device according to the present invention, a compression means for compressing image data and a first storage means for storing uncompressed image data of a plurality of frames in frame units. A second storage unit provided corresponding to the compression unit and storing the image data compressed by the corresponding compression unit in frame units, and an image compressed by the compression unit and stored in the second storage unit Image data expanding means for expanding data.

According to this structure, the image data of the frame frequently used in the image processing is stored in the first storage means without compression, and the image data of the frame used infrequently is compressed. It can be stored in the second storage means.

Therefore, an increase in the amount of processing for expanding the stored image data can be suppressed, and an increase in the amount of processing for compressing the stored image data can be suppressed.

Further, by compressing the image data of the frame which is not frequently used and storing the compressed image data in the second storage means, the storage capacity can be reduced.

As described above, in the image data storage device that stores the image data of a plurality of frames, it is possible to select an appropriate storage mode in consideration of the frequency of use for each frame. In addition, an appropriate storage mode can be selected in consideration of the image quality of the image data, the number of stored images, and the like, according to the purpose of use of the image data.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

In the image data storage device according to the present invention, a plurality of compression means for compressing image data, a first storage means for storing uncompressed image data of one or a plurality of frames in frame units, A plurality of second storage units, each of which stores image data compressed by the corresponding compression unit on a frame basis, and a second storage unit which is compressed by the compression unit. And image data decompression means for decompressing the image data stored in the storage means. The compression rates of the compression means are different from each other.

According to this configuration, the image data of the frame frequently used in the image processing is stored in the first storage means without compression, and the image data of the frame used less frequently is compressed. It can be stored in the second storage means.

Therefore, an increase in the amount of processing for expanding the stored image data can be suppressed, and an increase in the amount of processing for compressing the stored image data can be suppressed.

Further, as the frequency of use in image processing decreases, the image data is compressed by the compression means having a higher compression ratio and stored in the corresponding second storage means, thereby reducing the storage capacity. It can be achieved more effectively.

As described above, in the image data storage device that stores the image data of a plurality of frames, a more appropriate storage mode can be selected for each frame in consideration of the frequency of use. In addition, a more appropriate storage mode can be selected in consideration of the image quality of the image data, the number of stored images, and the like, according to the purpose of use of the image data.

As a result, the storage capacity can be more effectively reduced while suppressing an increase in the processing amount.

In the image data storage device according to the present invention, a plurality of compression means for compressing image data, a first storage means for storing uncompressed image data of one or more frames in frame units, A plurality of second storage units, each of which stores image data compressed by the corresponding compression unit on a frame basis, and a second storage unit which is compressed by the compression unit. And image data decompression means for decompressing the image data stored in the storage means, and the compression methods of the compression means are different from each other.

According to this configuration, the user can select whether to store the image data without compression or to store the image data after compressing the image data. Whether to memorize can be arbitrarily selected in frame units.

As a result, the storage capacity can be reduced while improving the convenience for the user.

[0046]

According to the first aspect of the present invention, there is provided an image data storage device comprising: a compression unit for compressing image data; a first storage unit for storing uncompressed image data of a plurality of frames in frame units; A second storage unit provided corresponding to the compression unit and storing the image data compressed by the corresponding compression unit in a frame unit; and image data compressed by the compression unit and stored in the second storage unit Image data expanding means for expanding the image data.

According to this configuration, the image data of the frame frequently used in the image processing is stored in the first storage means without compression, and the image data of the frame used less frequently is compressed. It can be stored in the second storage means.

Therefore, an increase in the amount of processing for expanding the stored image data can be suppressed, and an increase in the amount of processing for compressing the stored image data can be suppressed.

Also, the image data of a frame that is used less frequently is compressed and stored in the second storage means, so that the storage capacity can be reduced.

As described above, in the image data storage device that stores the image data of a plurality of frames, it is possible to select an appropriate storage mode in consideration of the frequency of use for each frame. In addition, an appropriate storage mode can be selected in consideration of the image quality of the image data, the number of stored images, and the like, according to the purpose of use of the image data.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

In the image data storage device according to the second aspect,
A plurality of compression means for compressing image data; a first storage means for storing uncompressed image data of one or more frames in frame units; and a plurality of compression means provided corresponding to the plurality of compression means. A plurality of second storage means for storing the image data compressed by the corresponding compression means in frame units; and image data decompression means for decompressing the image data stored in the second storage means by being compressed by the compression means And the compression ratio of each of the compression means is different from each other.

According to this configuration, the image data of the frame frequently used in the image processing is stored in the first storage means without compression, and the image data of the frame used less frequently is compressed. It can be stored in the second storage means.

Therefore, an increase in the amount of processing for expanding the stored image data can be suppressed, and an increase in the amount of processing for compressing the stored image data can be suppressed.

Further, as the frequency of use in the image processing decreases, the image data is compressed by the compression means having a higher compression ratio and stored in the corresponding second storage means, thereby reducing the storage capacity. It can be achieved more effectively.

As described above, in the image data storage device that stores the image data of a plurality of frames, a more appropriate storage mode can be selected for each frame in consideration of the frequency of use. In addition, a more appropriate storage mode can be selected in consideration of the image quality of the image data, the number of stored images, and the like, according to the purpose of use of the image data.

As a result, it is possible to more effectively reduce the storage capacity while suppressing an increase in the processing amount.

In the image data storage device according to the third aspect,
The predetermined compression means or means performs lossless compression, and the other compression means performs lossy compression.

According to this configuration, image data with a high frequency of use is stored in the first storage means without compression, and image data with a low frequency of use is reversibly compressed and stored in the second image data storage means. The image data that is stored and that is used less frequently can be lossy-compressed and stored in the second storage unit.

Alternatively, according to the priority determined in consideration of the image quality of the image data, the number of storages, etc., according to the purpose of use of the image data, the image data having the higher priority is not compressed and stored in the first storage means. The image data having a low priority is losslessly compressed and stored in a second image data storage means, and the image data having a low priority is lossy compressed and stored in a second storage means. Can be.

As described above, in the image data storage device that stores the image data of a plurality of frames, a more appropriate storage mode can be selected, so that the storage capacity can be reduced in consideration of suppressing the increase in the processing amount. This can be achieved even more effectively.

In the image data storage device according to the fourth aspect,
The image data decompression means includes a plurality of decompression means provided corresponding to the plurality of compression means, and the decompression means compresses the image data compressed by the corresponding compression means and stored in the corresponding second storage means. Elongate.

According to this configuration, the storage capacity can be reduced while suppressing an increase in the processing amount.

In the image data storage device according to the fifth aspect,
The compression unit compresses the image data by thinning out the pixel data, and the image data expansion unit expands the image data compressed by the compression unit by interpolating the pixel data.

According to this configuration, the compression processing and the decompression processing of the image data can be performed at high speed. This is because the thinning process and the interpolation process are relatively simple processes.

In a case where a plurality of compression means are provided and a plurality of second storage means are correspondingly provided, the image data stored in a certain second storage means is
When the storage mode is changed and stored in another second storage unit, the compression process can be performed without performing the decompression process. This is because image data compressed by thinning is stored in the second storage means.

Therefore, the processing for storing the image data stored in a certain second storage means in another storage means can be performed at a high speed by changing the storage mode.

When a plurality of compression means are provided and a plurality of second storage means are provided correspondingly, the image data decompression means can be shared by the plurality of second storage means. This is because the compression processing is performed by thinning, and the expansion processing is performed by interpolation accordingly. Therefore, the circuit scale can be reduced.

In the image data storage device according to the sixth aspect,
The compression means compresses the image data by reducing a predetermined block from a plurality of blocks composed of frequency domain components obtained by performing a wavelet transform on the image data, and the image data decompression means The image data compressed by the compression unit is interpolated with the predetermined data deleted by the compression with the predetermined data and subjected to an inverse wavelet transform with respect to the image data compressed by the compression unit. Elongate.

According to this configuration, when a plurality of compression units are provided and a plurality of second storage units are provided correspondingly, the image data stored in a certain second storage unit is When the storage mode is changed and stored in another second storage unit, the compression process can be performed without performing the decompression process. This is because the second storage unit stores a block including frequency domain components obtained by the wavelet transform.

Accordingly, it is possible to change the storage form of the image data stored in a certain second storage means and to store the image data in another second storage means at a high speed.

When a plurality of compression means are provided and a plurality of second storage means are provided correspondingly, the image data decompression means can be shared by the plurality of second storage means. This is because the compression processing is performed by wavelet transform and deletion of blocks composed of frequency domain components, and accordingly, the expansion processing is performed by interpolation of blocks composed of frequency domain components and inverse wavelet transform. Because it is Therefore, the circuit scale can be reduced.

Further, since low-frequency components are more important to human vision than high-frequency components of image data, if they are deleted from high-frequency components at the time of compression by the compression means, they can be removed by humans. Low-frequency area components that are important for vision remain, and deterioration of the image quality of the image after image processing using the decompressed image data can be reduced.

In the image data storage device according to the seventh aspect,
The first storage means, the second storage means, the compression means, and the image data decompression means correspond to the first storage means and the second storage means.
And control means for giving an instruction to change the storage mode of the image data stored in the storage means.

According to this configuration, the image data stored in the first storage means and the second storage means can be updated.

In the image data storage device according to the eighth aspect,
Control means for giving an instruction to the first storage means, the second storage means, and the compression means to change the storage mode of the image data stored in the first storage means and the second storage means Is further provided.

According to this configuration, the image data stored in the first storage means and the second storage means can be updated.

Further, since the image data decompression means is not used in the updating process, the speed of the updating process can be increased.

In the image data storage device according to the ninth aspect,
The compression means performs compression in block units of m × n (m and n are natural numbers) pixels, and the image data decompression means performs m × n
(M and n are natural numbers) Decompression is performed in units of pixel blocks.

According to this configuration, the image data can be read out from the first storage means or the second storage means for storing the image data in frame units in block units of m × n pixels.

According to a tenth aspect of the present invention, there is provided an image data storage device comprising: a plurality of compression means for compressing image data; a first storage means for storing uncompressed image data of one or more frames in frame units; A plurality of second storage units provided corresponding to the plurality of compression units, each of which stores the image data compressed by the corresponding compression unit in a frame unit; And image data decompression means for decompressing the image data stored in the means. The compression methods of the compression means are different from each other.

According to this configuration, the user can select whether to store the image data without compression or to store the image data after compression. Whether to memorize can be arbitrarily selected in frame units.

As a result, the storage capacity can be reduced while improving the convenience for the user.

According to an eleventh aspect of the present invention, there is provided an encoding apparatus comprising the image data storage device according to the first aspect, wherein inter-picture prediction is performed using image data of a frame stored in the image data storage device as image data of a reference frame. Apply encoding.

According to this configuration, when a plurality of frames can be used as reference frames for encoding,
For each reference frame, an appropriate storage mode can be selected in consideration of the frequency of use.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

According to the twelfth aspect of the present invention, a predetermined number of past frames that are temporally continuous with respect to the current frame to be encoded and the current frame to be encoded are set. , In a frame group consisting of
Each group comprises a plurality of groups of a predetermined number of frames, the past frames are reference frames when performing inter prediction, and the group including the current encoding target frame is at least The image data storage device includes one reference frame, and the compression unit of the image data storage device is provided corresponding to a group including only the reference frame, and compresses the image data of the reference frame belonging to the corresponding group. The first storage means is provided corresponding to the group including the current frame to be encoded, stores uncompressed image data of frames belonging to the corresponding group, and stores the second image data of the second frame of the image data storage device.
Storage means are provided corresponding to a group consisting of only reference frames, and are compressed by the corresponding compression means.
The image data of the reference frame belonging to the corresponding group is stored.

According to this configuration, the reference frame temporally close to the current encoding target frame is stored without compression, and the reference frame temporally far from the current encoding target frame is compressed. Is memorized.

That is, the image data of the reference frame that is frequently used is stored without compression, and the image data of the reference frame that is not frequently used is compressed and stored.

Accordingly, a small storage area can be allocated to a reference frame which is not frequently used.

As described above, when a plurality of frames can be used as reference frames for encoding, each reference frame is stored in an appropriate storage form in consideration of the frequency of use.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

According to a thirteenth aspect of the present invention, there is provided an encoding device comprising the image data storage device according to the second aspect, wherein inter-picture prediction is performed using image data of a frame stored in the image data storage device as image data of a reference frame. Apply encoding.

According to this configuration, when a plurality of frames can be used as reference frames for encoding,
For each frame, a more appropriate storage mode can be selected in consideration of the frequency of use.

As a result, the storage capacity can be more effectively reduced while suppressing an increase in the processing amount.

[0096] In the encoding apparatus according to the fourteenth aspect, a predetermined number of past frames that are temporally continuous with respect to the current frame to be encoded, and the current frame to be encoded. , In a frame group consisting of
Each group comprises a plurality of groups of a predetermined number of frames, the past frames are reference frames when performing inter-screen prediction, and the group including the current encoding target frame is the current frame. Consists of only the encoding target frame, or consists of the current encoding target frame and a reference frame, and a plurality of compression means of the image data storage device correspond to a plurality of groups consisting only of the reference frame. A compression unit configured to compress image data of a reference frame belonging to a corresponding group, and a first storage unit of the image data storage device is provided corresponding to a group including a frame to be currently encoded. And stores the uncompressed image data of the frames belonging to the corresponding group, and the plurality of second storage units of the image data storage device Each of the second storage means is provided corresponding to a plurality of groups consisting only of frames, and stores the image data of the reference frame belonging to the corresponding group, which is compressed by the corresponding compression means. The rate is greater than the compression rate of the compression unit corresponding to the group including the reference frame temporally closer to the current encoding target frame than the reference frame belonging to the group corresponding to the compression unit.

According to this configuration, the reference frame is compressed and stored at a high compression rate as the time becomes farther from the current frame to be encoded.

That is, the reference frame is compressed and stored at a high compression rate as the frequency of use decreases.

Therefore, as the frequency of use decreases, 1
The storage area allocated to one reference frame can be reduced step by step in groups.

As described above, when a plurality of frames can be used as reference frames for encoding, each reference frame is stored in a more appropriate storage form in consideration of the frequency of use.

As a result, the storage capacity can be more effectively reduced while suppressing an increase in the processing amount.

A decoding device according to a fifteenth aspect includes the image data storage device according to the first aspect, wherein inter-picture prediction is performed using image data of a frame stored in the image data storage device as image data of a reference frame. Perform decryption.

According to this configuration, when a plurality of frames can be used as reference frames for decoding,
For each reference frame, an appropriate storage mode can be selected in consideration of the frequency of use.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

In the decoding device according to the sixteenth aspect, a predetermined number of past frames that are temporally continuous with respect to the current frame to be decoded and the current frame to be decoded are set. , In a frame group consisting of
Each group comprises a plurality of groups of a predetermined number of frames, the past frames are reference frames when performing inter-picture prediction, and the group including the current decoding target frame is at least The image data storage device includes one reference frame, and the compression unit of the image data storage device is provided corresponding to a group including only the reference frame, and compresses the image data of the reference frame belonging to the corresponding group. The first storage means is provided corresponding to the group including the current frame to be decoded, stores the uncompressed image data of the frames belonging to the corresponding group, and stores the second image data of the second frame of the image data storage device.
Storage means are provided corresponding to a group consisting of only reference frames, and are compressed by the corresponding compression means.
The image data of the reference frame belonging to the corresponding group is stored.

According to this configuration, the reference frame temporally close to the current frame to be decoded is stored without compression, and the reference frame temporally far from the current frame to be decoded is compressed. Is memorized.

That is, the image data of the reference frame that is frequently used is stored without compression, and the image data of the reference frame that is not frequently used is compressed and stored.

Therefore, a small storage area can be allocated to a reference frame that is not frequently used.

As described above, when a plurality of frames can be used as reference frames for decoding, each reference frame is stored in an appropriate storage form in consideration of the frequency of use.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

[0111] A decoding device according to claim 17 is provided with the image data storage device according to claim 2, and uses inter-picture prediction by using image data of a frame stored in the image data storage device as image data of a reference frame. Perform decryption.

According to this configuration, when a plurality of frames can be used as reference frames for decoding,
For each frame, a more appropriate storage mode can be selected in consideration of the frequency of use.

As a result, it is possible to more effectively reduce the storage capacity while suppressing an increase in the processing amount.

In the decoding apparatus according to the eighteenth aspect, a predetermined number of past frames that are temporally continuous with respect to the current frame to be decoded and the current frame to be decoded are set. , In a frame group consisting of
Each group comprises a plurality of groups of a predetermined number of frames, the past frames are reference frames when performing inter-picture prediction, and the group including the current frame to be decoded is the current frame. Consists of only the frame to be decoded, or consists of the current frame to be decoded and a reference frame, and a plurality of compression means of the image data storage device correspond to a plurality of groups consisting only of the reference frame. The compression means is provided for compressing image data of a reference frame belonging to a corresponding group, and the first storage means of the image data storage device is provided corresponding to the group including the current frame to be decoded. And stores the uncompressed image data of the frame belonging to the corresponding group, and the plurality of second storage units of the image data storage device Each of the second storage means is provided corresponding to a plurality of groups consisting only of frames, and stores the image data of the reference frames belonging to the corresponding group, which are compressed by the corresponding compression means. The compression ratio is larger than the compression ratio of the compression unit corresponding to the group including the reference frame temporally closer to the current frame to be decoded than the reference frame belonging to the group corresponding to the compression unit.

According to this configuration, the reference frame is compressed and stored at a high compression rate as it becomes temporally farther from the current frame to be decoded.

That is, the reference frame is compressed and stored at a high compression rate as the frequency of use decreases.

Therefore, as the frequency of use decreases, 1
The storage area allocated to one reference frame can be reduced step by step in groups.

As described above, when a plurality of frames can be used as reference frames for decoding, each reference frame is stored in a more appropriate storage form in consideration of the frequency of use.

As a result, it is possible to more effectively reduce the storage capacity while suppressing an increase in the processing amount.

In the compression / decompression system according to claim 19,
An encoding device according to claim 11 and a decoding device according to claim 15, wherein the encoding device is configured to store information relating to compression of image data by an image data storage device, And multiplexing means for generating multiplexed data, and the decoding apparatus further includes a separating means for separating the received multiplexed data into information on compression and encoded image data. Prepare.

According to this configuration, the image data storage device of the decoding device can perform compression and decompression using the information on compression used in the image data storage device of the encoding device.

Therefore, even when the reference frame is irreversibly compressed and stored and decompressed in the image data storage device of the decoding device, the reference frame is the same in the encoding device and the decoding device.

As a result, it is possible to prevent the image quality from being degraded due to the inconsistency of the image data of the reference frame between the encoding device and the decoding device, and also to prevent the image data storage device of the encoding device and the decoding device from using the same. The storage capacity can be reduced.

In the compression / decompression system according to the twentieth aspect,
An encoding device according to claim 13 and a decoding device according to claim 17, wherein the encoding device is configured to store information relating to compression of image data by an image data storage device, And multiplexing means for generating multiplexed data, and the decoding apparatus further includes a separating means for separating the received multiplexed data into information on compression and encoded image data. Prepare.

According to this configuration, the image data storage device of the decoding device can perform compression and decompression using the information on compression used in the image data storage device of the encoding device.

Therefore, even when the reference frame is irreversibly compressed, stored and decompressed in the image data storage device of the decoding device, the reference frame is the same in the encoding device and the decoding device.

As a result, while preventing the image quality from being deteriorated due to the inconsistency of the image data of the reference frame between the encoding device and the decoding device, the image data storage devices of the encoding device and the decoding device can be prevented. The storage capacity can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. (Embodiment 1)

FIG. 1 is a block diagram of an image data storage device according to the first embodiment of the present invention.

As shown in FIG. 1, this image data storage device comprises an image data compression means 1, an image data storage means 2,
An image data decompression unit 3 and a control unit 4 are provided.

The image data compression means 1 includes I ("I" is an integer of 1 or more) compression circuits A1, A2,..., AI.

Here, when the compression circuits A1, A2,..., AI are comprehensively represented, they are referred to as compression circuits Ai.

The image data storage means 2 has J ("J" is an integer of 1 or more) frame memories M1, M2,.
including.

Here, the frame memories M1, M2,...
When MJ is comprehensively expressed, it is referred to as a frame memory Mj.

The image data decompression means 3 includes I ("I" is an integer of 1 or more) decompression circuits B1, B2,..., BI. The decompression circuits B1, B2,...
1, A2,..., AI.

Here, when the expansion circuits B1, B2,..., BI are comprehensively expressed, they are referred to as expansion circuits Bi.

The control means 4 includes a memory control means 41 and a control circuit 42.

First, the operation of the image data storage device shown in FIG. 1 will be briefly described. The data bus 5 receives image data input from outside the image data storage device or from the data bus 8.

Then, the data bus 5 outputs the input image data to the compression circuit Ai of the image data compression means 1 or the data bus 6.

The compression circuit Ai of the image data compression means 1
Compress input image data. The data bus 6 is connected to the data bus 5 or the compression circuit Ai of the image data compression means 1.
Input the image data output by.

The data bus 6 stores the input image data in the frame memory Mj of the image data storage means 2.
Output to

The frame memory M of the image data storage means 3
j stores image data input from the data bus 6 in frame units.

The data bus 7 receives the image data output from the frame memory Mj of the image data storage means 2 as an input.

Then, the data bus 7 outputs the input image data to the data bus 8 or the expansion circuit Bi of the image data expansion means 3.

The decompression circuit Bi of the image data decompression means 3
Decompress input image data. The data bus 8 is connected to the decompression circuit Bi of the image data decompression means 3 or the data bus 7.
Input the image data output by.

Then, the data bus 8 outputs the input image data to the outside of the image data storage device or to the data bus 5.

The control means 4 controls the image data compression means 1, the image data storage means 2, and the image data decompression means 3 based on a control signal S inputted from outside the image data storage device.

Next, the operation of the image data storage device of FIG. 1 will be described in detail. Image data is input to the data bus 5 from outside the image data storage device in units of macroblocks of 16 × 16 pixels.

On the other hand, the storage mode for storing the image data in the image data storage means 2 is specified to the control means 4 by a control signal S input from the outside.

This storage mode includes a mode in which image data is stored without compression, and a mode in which image data is compressed and stored.

Further, the image data can be compressed and stored in the form of compression and storage in the compression circuit A1, the compression and storage in the compression circuit A2,..., And compressed and stored in the compression circuit AI. There are I forms called forms.

The designation of the storage mode by the control signal S is performed on a frame basis.

The control means 4 receiving the control signal S indicating that the storage mode is a mode for storing image data without compression.
Then, the control circuit 42 controls the data bus 5 to supply the image data input to the data bus 5 to the data bus 6.

On the other hand, the control circuit 42 controls the data bus 5 by specifying the compression circuit Ai and receiving the control signal S indicating that the storage mode is a mode for compressing and storing image data. Then, the image data input to the data bus 5 is supplied to the compression circuit Ai specified by the control signal S.

The compression circuit Ai is controlled by the control circuit 4
According to the instruction of 2, the image data input from the data bus 5 is compressed and output to the data bus 6.

At the time of compression, between the compression circuit Ai and the control circuit 42, parameters at the time of compression (hereinafter, referred to as "compression parameters"), control signals such as start / end of compression, the number of code bits, etc. Are exchanged.

Each of the compression circuits A1 to AI reduces the amount of compressed image data per frame by the compression circuit A.
i has different compression schemes and compression ratios.

That is, the compression ratios of the compression circuits A1 to AI are different from each other. The compression circuits A1 to AI
The compression ratios may be different from each other, and the compression schemes may be the same or different.

The compression method provided in the compression circuit Ai includes:
For example, a method of entropy coding differential data of adjacent pixels using spatial correlation in a screen, DCT (dis
A method of performing orthogonal transformation such as create cosine transform) to perform frequency transformation and entropy encoding of quantized data, a sub-band encoding method such as wavelet transformation, or down-sampling by down-sampling at regular intervals. Method, and so on.

Now, the data bus 5 is directly connected to the data bus 6
The non-compressed image data input to the data bus 6 and the compressed image data input to the data bus 6 from the compression circuit Ai are written to any of the frame memories M1 to MJ.

When writing image data to the frame memory Mj, the memory control means 41 designates a frame memory Mj for writing image data and an address in the frame memory Mj for writing.

Further, the memory control means 41 stores information (referred to as image data storage in the frame memory Mj) so that the image data stored in the image data storage means 2 can be arbitrarily output to the outside in macroblock units. Less than,
It is called “storage-related information”. ) Hold.

FIG. 2 is an explanatory diagram of the first storage-related information held by the memory control means 41. As shown in FIG.
The first storage-related information includes, for each of the frame memories M1 to MJ, a stored frame number, a storage mode,
And a compression parameter necessary at the time of decompression.

"M1 to M" in the column of the frame memory in FIG.
“J” corresponds to the symbols M1 to MJ assigned to the frame memories M1 to MJ in FIG.

The column of frame number describes the identification number of the frame stored in each of the frame memories M1 to MJ.

“A0” shown in the column of the storage format indicates that the storage format is a format for storing without compression.

"A1 to AI" shown in the column of storage mode
Are the symbols A1 to AI assigned to the compression circuits A1 to AI in FIG.
For example, “A1” in the column of the storage mode is
This indicates that the storage mode is a mode in which the data is compressed and stored by the compression circuit A1.

In the column of compression parameters, each compression circuit A1
~ Compression parameters (parameters used during compression) are described.

FIG. 3 is an explanatory diagram of the second storage related information held by the memory control means 41. Memory control means 41
Holds the second storage related information as shown in FIG. 3 for each of the frame memories M1 to MJ.

As shown in FIG. 3, the second storage-related information includes, for a macroblock number of a stored frame, a head address of a storage area in which image data of the macroblock number is stored. Is related.

Note that “K” in the macroblock number column in FIG. 3 represents the number of macroblocks included in one frame.

The description so far is for writing image data in the frame memory Mj. When reading image data from the frame memory Mj, information indicating the number of the frame to which the macroblock to be read belongs and information indicating the number of the macroblock to be read are externally given to the control means 4 as a control signal S.

The memory control means 41 refers to the first storage-related information (FIG. 2) and determines, from the number of the frame to which the macroblock to be read belongs, the frame in which the frame to which the macroblock to be read belongs is stored. Specify the memory Mj.

Further, referring to the second storage related information (FIG. 3), the memory control means 41 determines the number of the macro block to be read and the head of the storage area in which the image data of the macro block to be read is stored. Identify the address.

Then, the memory control means 41, for the corresponding frame memory Mj,
An instruction is issued to output image data of a macro block to be read to the data bus 7.

The frame memory Mj receiving this instruction stores
The image data of the macro block to be read is output to the data bus 7 from the corresponding storage area.

When the image data of the macro block to be read, which is input to the data bus 7, is not compressed,
The image data is directly output to the data bus 8.

On the other hand, when the image data of the macro block to be read which is input to the data bus 7 is compressed, the memory control means 41 should read with reference to the first storage related information (FIG. 2). The storage mode of the image data is specified from the number of the frame to which the macro block belongs.

Further, the memory control means 41 uses the compression circuit Ai for compressing the image data from the specified storage mode.
To identify.

The control circuit 42 controls the data bus 7 to control the compression circuit Ai specified by the memory control means 41.
The image data of the macro block to be read, which is input to the data bus 7, is output to the decompression circuit Bi corresponding to

The compression circuit A specified by the memory control means 41
The decompression circuit Bi corresponding to i receives the compression parameter of the first storage related information from the memory control means 41,
Based on the compression parameter, the image data of the macro block to be read, which is input from the data bus 7, is expanded. The decompressed image data is output to the data bus 8.

The image data of the macro block to be read, which has been input to the data bus 8, is sequentially output to the outside.

The I decompression circuits B1 to BI and the I compression circuits A1 to AI have a one-to-one correspondence, and the decompression circuit Bi decompresses the image data compressed by the corresponding compression circuit Ai. I do.

That is, the decompression circuit Bi has a decompression method corresponding to the corresponding compression circuit Ai.

When an external control signal S instructs the control means 4 to change the storage mode of the image data stored in the image data storage means 2, the following is performed. Processing is performed.

In this case, the information indicating the new storage mode, the information indicating the number of the frame to which the macroblock whose storage mode should be changed belongs, and the information indicating the number of the macroblock whose storage mode should be changed are externally supplied to the control means. 4 as a control signal S.

The memory control means 41 refers to the first storage-related information (FIG. 2) and determines the number of the frame to which the storage mode to be changed belongs from the number of the frame to which the storage mode is to be changed. The frame memory Mj storing the frame to which the frame belongs is specified.

Further, the memory control means 41 refers to the second storage-related information (FIG. 3) and determines the image data of the macro block whose storage mode is to be changed from the number of the macro block whose storage mode is to be changed. Identify the start address of the stored storage area.

Then, the memory control means 41 sends the relevant frame memory Mj from the relevant storage area
An instruction is issued to output image data of a macroblock whose storage mode is to be changed to the data bus 7.

Upon receiving this instruction, the frame memory Mj
The image data of the macro block whose storage mode is to be changed is output to the data bus 7 from the corresponding storage area.

If the image data of the macroblock whose storage mode is to be changed and which is input to the data bus 7 is not compressed, the image data is directly output to the data bus 8.

On the other hand, when the image data of the macro block whose storage mode is to be changed, which is input to the data bus 7, is compressed, the memory control means 41 refers to the first storage related information (FIG. 2). Then, the storage mode of the image data is specified from the number of the frame to which the macroblock whose storage mode should be changed belongs.

Further, the memory control means 41 uses a compression circuit Ai for compressing the image data from the specified storage mode.
To identify.

Then, the control circuit 42 controls the data bus 7 so that the compression circuit Ai
The image data of the macro block whose storage mode is to be changed, which is input to the data bus 7, is output to the decompression circuit Bi corresponding to.

The compression circuit A specified by the memory control means 41
The decompression circuit Bi corresponding to i receives the compression parameter of the first storage related information from the memory control means 41,
Based on the compression parameter, the image data of the macroblock whose storage mode is to be changed, which is input from the data bus 7, is expanded. The decompressed image data is output to the data bus 8.

The control circuit 42 outputs to the data bus 5 the image data of the macroblock whose storage mode is to be changed, which is input to the data bus 8.

Further, the control circuit 42 controls the data bus 5 to supply the image data of the macro block whose storage mode is to be changed, which is input to the data bus 5, to the compression circuit Ai corresponding to the new storage mode. .

The compression circuit Ai is controlled by the control circuit 4
2, the image data of the macroblock whose storage mode is to be changed, which is input from the data bus 5, is compressed,
Output to the data bus 6.

The control circuit 42 refers to the first storage-related information (FIG. 2) and specifies the frame memory Mj for storing the image data of the macroblock whose storage mode is to be changed from the information on the new storage mode. I do.

Then, the control circuit 42 controls the data bus 6 to supply the specified frame memory Mj with the image data of the macro block whose storage mode is to be changed, input to the data bus 6.

[0201] The frame memory Mj stores the image data of the macroblock whose storage mode is to be changed, which is input from the data bus 6. As described above, the storage mode is changed.

In the present embodiment, assuming that I (the number of compression circuits Ai and decompression circuits Bi) = 1 and J (the number of frame memories Mj) = 2, the frame memory M1 for storing uncompressed image data is provided. Assume that image data of a plurality of frames is stored.

In this case, the image data of the frame frequently used in the image processing is stored in the frame memory M1 without being compressed, and the image data of the frame used infrequently is compressed and stored in the frame memory M2. Can be memorized.

Therefore, an increase in the amount of processing for expanding the stored image data can be suppressed, and an increase in the amount of processing for compressing the stored image data can be suppressed.

Further, by compressing the image data of the frame which is not frequently used and storing it in the frame memory M2, the storage capacity can be reduced.

As described above, in the image data storage device that stores the image data of a plurality of frames, it is possible to select an appropriate storage mode in consideration of the frequency of use for each frame.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

In the present embodiment, “I (the number of compression circuits Ai and decompression circuits Bi)” is 2 or more, and “J (the number of frame memories Mj)” is 3 or more. It is assumed that the storing frame memory M1 stores image data of one or a plurality of frames.

In this case, the image data of the frame frequently used in the image processing is stored in the frame memory M1 without being compressed, and the image data of the frame used infrequently is compressed and stored in the frame memory M2. It can be stored in the MJ.

Therefore, it is possible to suppress an increase in the amount of processing for expanding the stored image data, and to suppress an increase in the amount of processing for compressing the stored image data.

Further, as the frequency of use in image processing decreases, image data is compressed by a compression circuit Ai having a higher compression ratio and stored in the corresponding frame memory Mj, thereby further reducing the storage capacity. It can be achieved effectively.

As described above, in the image data storage device that stores the image data of a plurality of frames, a more appropriate storage mode can be selected for each frame in consideration of the frequency of use.

As a result, the storage capacity can be more effectively reduced while suppressing an increase in the processing amount.

In the present embodiment, the data processing unit of the accumulation processing in the frame memory Mj and the output processing from the frame memory Mj has been described as a macroblock unit of 16 × 16 pixels.

However, the data processing unit is not limited to the macro block unit. For example, 8 × 8 pixels,
The block size serving as a data processing unit, such as 8 × 16 pixels, can be arbitrarily determined.

The image data storage device shown in FIG. 1 can be used, for example, for storing moving images.

The image data storage device shown in FIG. 1 can be used for storing a still image, for example. Then, an appropriate storage mode can be selected in consideration of the image quality of the image data, the number of stored images, and the like according to the purpose of use of the image data. Therefore, also in this case, the storage capacity can be reduced while suppressing an increase in the processing amount.

For example, a very favorite still image is stored without compression, a favorite still image is simply compressed and stored at a low compression ratio by lossless compression, and a still image to be temporarily stored is large by irreversible compression. It can be compressed and stored at the compression ratio.

In the image data storage device shown in FIG. 1, the compression ratios of the compression circuits A1 to AI are different from each other.

However, the present invention is not limited to this.
For example, the compression schemes of the compression circuits A1 to AI may be different from each other. In this case, the compression ratios of the compression circuits A1 to AI may be the same as each other or may be different.

Thus, the user can select whether to store the image data without compression, or to store the image data after compression, and if compression is to be performed, which compression method should be used to store the image data. , Can be arbitrarily selected in frame units.

As a result, it is possible to reduce the storage capacity while improving the convenience for the user.

(Embodiment 2) A moving picture compression / decompression system according to Embodiment 2 of the present invention includes a moving picture coding apparatus and a moving picture decoding apparatus. First, the moving picture coding apparatus will be described.

FIG. 4 is a block diagram of a moving picture coding apparatus according to Embodiment 2 of the present invention.

As shown in FIG. 4, the moving picture coding apparatus comprises a subtracter 10, an orthogonal transform circuit 20, a quantizing circuit 30,
A variable length encoding circuit 40, an inverse quantization circuit 50, an inverse orthogonal transform circuit 60, an adder 70, an image data storage device 80, a motion compensation circuit 90, and a motion detection circuit 100.

This moving picture coding apparatus is based on H.264. The present invention realizes encoding in a hybrid format by a combination of motion compensation and orthogonal transform used in a moving image encoding method such as H.263 or MPEG-4.

The image data storage device 80 is the same as the image data storage device according to the first embodiment shown in FIG.

In the coding method of this moving picture coding apparatus, an image that can be referred to in motion compensation (hereinafter referred to as a “reference frame”) is composed of a plurality of frames that have been coded before the current frame. And

Note that the reference frame is a frame earlier than the encoding target frame.

Next, the flow of processing in the moving picture coding apparatus shown in FIG. 4 will be described. When moving image data is input to the moving image encoding device, first, the motion detection circuit 100 detects a motion vector.

The motion detection circuit 100 uses the video data to be encoded input from outside the video encoding device and the image data of the reference frame input from the image data storage device 80, Detect motion vector,
Output to the motion compensation circuit 90.

The motion compensation circuit 90 includes a motion detection circuit 100
The motion vector input from the
Motion compensation is performed using the reference frame image data input from 0.

The subtracter 10 subtracts the motion-compensated image data input from the motion compensation circuit 90 from the video data to be encoded used for motion detection, obtains difference data, and obtains the difference data. 20.

The processing up to this point is for the case where motion compensation is performed. In the case where no difference is taken between frames and motion compensation is not performed, the moving image data input from the outside is subtracted by a subtractor. The signal is directly input to the orthogonal transformation circuit 20 without performing the processing by 10.

The orthogonal transformation circuit 20 performs an orthogonal transformation process on the input image data, and outputs the result to the quantization circuit 30.

The quantization circuit 30 performs a quantization process on the input image data and outputs the result to the variable length coding circuit 40.

The variable-length coding circuit 40 performs variable-length coding on the input image data, and outputs it as moving image coded data to the outside.

On the other hand, a process called local decoding is performed. The quantization circuit 30 outputs the quantized image data to the variable-length encoding circuit 40 and to the inverse quantization circuit 50 at the same time.

The inverse quantization circuit 50 performs an inverse quantization process on the input image data using the same quantization table as that used when the quantization circuit 30 performs quantization, and outputs the result to the inverse orthogonal transform circuit 60.

The inverse orthogonal transform circuit 60 performs an inverse orthogonal transform process on the input image data, and outputs the result to the adder 70 or the image data storage device 80.

In this case, when the image data input to the inverse orthogonal transform circuit 60 has been subjected to motion compensation,
The image data subjected to the inverse orthogonal transform processing is output to the adder 70.

On the other hand, when the image data input to the inverse orthogonal transform circuit 60 has not been subjected to motion compensation, the image data subjected to the inverse orthogonal transform processing is stored as decoded image data in the image data storage. Output to the device 80.

The adder 70 adds the motion-compensated image data input from the motion compensation circuit 90 and the difference data, which is the image data input from the inverse orthogonal transform circuit 60, to form an orthogonal signal. The transformed and quantized image data is decoded and output to the image data storage device 80.

The image data storage device 80 stores the image data input from the inverse orthogonal transform circuit 60 and the image data input from the adder 70 as the image data of the reference frame in the encoding processing of the next frame. I do.

Next, a moving picture decoding apparatus according to Embodiment 2 will be described. FIG. 5 shows Embodiment 2 of the present invention.
3 is a block diagram of a video decoding device in FIG. In addition,
5, the same components as those in FIG. 4 are denoted by the same reference numerals, and the description will be appropriately omitted.

As shown in FIG. 5, this moving picture decoding apparatus comprises a variable length decoding circuit 110, an inverse quantization circuit 50, an inverse orthogonal transform circuit 60, an adder 70, and an image data storage device 8.
0 and a motion compensation circuit 90.

In this decoding method using the moving picture decoding apparatus, an image (reference frame) that can be referred to in motion compensation is decoded before the decoding target frame, as in the above moving picture coding apparatus. Multiple frames.

Note that the reference frame is a frame that is earlier than the frame to be decoded.

Next, the flow of processing in the moving picture decoding apparatus shown in FIG. 5 will be described. Variable length decoding circuit 110
Performs variable-length decoding on the input encoded video data and outputs the result to the inverse quantization circuit 50.

The inverse quantization circuit 50 performs an inverse quantization process on the input image data, and
Output to

If the input image data is image data compressed between frames, the inverse orthogonal transform circuit 60
The image data subjected to the inverse orthogonal transform processing is output to the adder 70.

On the other hand, when the input image data is not image data compressed between frames, the inverse orthogonal transform circuit 50 converts the image data subjected to the inverse orthogonal transform process into decoded moving image data to the external and the image data. Data storage device 80
Output to

The adder 70 adds the motion-compensated image data input from the motion compensation circuit 90 and the difference data that is the image data input from the inverse orthogonal transform circuit 60, and adds the added data. The result is output to the external and image data storage device 80 as decoded moving image data.

The image data storage device 80 stores the image data input from the inverse orthogonal transform circuit 60 and the image data input from the adder 70 as the image data of the reference frame in the decoding processing of the next frame. I do.

The motion compensating circuit 90 includes the variable length decoding circuit 1
10 and receives the motion vector decoded and input from the image data 10 and the image data of the reference frame input from the image data storage device 80, and performs motion compensation.

Next, the details of the image data storage device 80 in the video decoding device of FIG. 5 will be described.

FIG. 6 is a block diagram of the image data storage device 80 in the moving picture decoding device of FIG. In FIG. 6, the same components as those in FIG.

As shown in FIG. 6, the image data storage device 80 of FIG. 5 includes an image data compression unit 1, an image data storage unit 2, an image data decompression unit 3, and a control unit 4.

The image data compression means 1 comprises a compression circuit A1,
A2 and A3 are included.

The image data storage means 2 includes frame memories M1, M2, M3, M4. Frame memory M1
Includes frame regions M1a and M1b. The frame memory M2 includes frame areas M2a and M2b. The frame memory M3 includes frame areas M3a and M3b.
The frame memory M4 includes frame areas M4a, M4b,
M4c and M4d.

The frame memories M2 to M4 are provided corresponding to the compression circuits A1 to A3, respectively.

The image data decompression means 3 comprises a decompression circuit B1,
B2 and B3. The decompression circuits B1 to B3 are provided corresponding to the compression circuits A1 to A3, respectively.

The control means 4 includes a memory control means 41 and a control circuit 42. The memory control means 41 includes memory control circuits MC1, MC2, MC3, MC4.

Note that the memory control circuits MC1 to MC4
They are provided corresponding to the frame memories M1 to M4, respectively.

Next, the function and operation of each component shown in FIG. 6 will be described. First, the image data storage unit 2 will be described.

The frame memory M1 stores a frame to be decoded and a frame (reference frame) that can be referred to in decoding. Specifically, it is as follows.

The frame areas M1a and M1b are obtained by dividing the address area of the frame memory M1 into two.

The frame areas M1a and M1b are
Each stores one frame of image data.

One of the two frame areas M1a and M1b stores a frame to be decoded, and the other stores a reference frame.

The frame memories M2 and M3 are respectively
Two reference frames are stored. Specifically, it is as follows.

The frame areas M2a and M2b are obtained by dividing the address area of the frame memory M2 into two.
The frame areas M3a and M3b are obtained by dividing the address area of the frame memory M3 into two.

The frame areas M2a, M2b, M
Each of 3a and M3b stores image data of one frame (image data of a reference frame).

The frame memory M4 stores four reference frames. Specifically, it is as follows.

Frame areas M4a, M4b, M4c, M
4d divides the address area of the frame memory M4 into four.

The frame areas M4a, M4b, M
4c and M4d each store image data for one frame (image data of a reference frame).

As can be seen from the above, in the present embodiment, the number of reference frames is nine.

Next, the image data compression means 1 and the image data decompression means 3 will be described. The compression circuit A1 losslessly compresses and encodes the image data stored in the frame area M1a or M1b of the frame memory M1, compresses the data amount, and outputs the compressed data to the frame memory M2.

The decompression circuit B1 is losslessly compression-encoded by the compression circuit A, and is stored in the frame area M2a of the frame memory M2.
Alternatively, the image data stored in the frame area M2b is decoded and decompressed to the original image data.

The compression circuit A2 performs irreversible compression encoding on the image data expanded by the expansion circuit B1, compresses the data amount, and outputs the compressed data to the frame memory M3.

The expansion circuit B2 decodes the image data compressed and encoded by the compression circuit A2 and stored in the frame area M3a or M3b of the frame memory M3, and expands the original image data.

The compression circuit A3 performs lossy compression encoding on the image data expanded by the expansion circuit B2, compresses the data amount, and outputs the compressed data to the frame memory M4.

The decompression circuit B3 is compression-encoded by the compression circuit A3, and is decompressed by the frame area M4a of the frame memory M4.
The image data stored in the frame area M4b, M4c, or M4d is decoded and expanded to the original image data.

Here, the compression ratio of the compression circuit A1> the compression ratio of the compression circuit A2> the compression ratio of the compression circuit A3.

[0284] The compression encoding method of the compression circuit A1 is as follows.
If the compression circuits A2 and A3 are irreversible compression coding systems, the compression coding systems in the compression circuits A1 to A3 are the first embodiment.
Similarly to the compression circuit Ai in the above, the present invention is not limited to a specific compression encoding method.

Next, the control means 4 will be described. The memory control circuit MC1 generates and manages addresses when writing image data to the frame memory M1 and when reading image data from the frame memory M1.

Similarly, memory control circuits MC2 to MC4
Are used when image data is written into the corresponding frame memories M2 to M4, and when the corresponding frame memories M2 to M4 are written.
When the image data is read out from the memory 4, the address generation and management are performed.

Control circuit 42 includes memory control circuits MC1-MC1.
The MC 4 controls the image data compression means 1 and the image data decompression means 3.

Next, writing of image data in the image data storage means 2 will be described.

Frames are sequentially input to the image data storage device in FIG. 6, and a previously input frame is referred to as a previous frame based on a certain input frame.

Note that the previous frame may be referred to as a frame earlier than the reference frame.

A frame area M1a of the frame memory M1
The frame area M1b stores the image data of the decoding target frame and the image data of the reference frame one frame before the decoding target frame.

A frame area M2a of the frame memory M2
And the frame area M2b stores image data of a reference frame two frames before and three frames before the decoding target frame.

The frame area M3a of the frame memory M3
And the frame area M3b stores image data of a reference frame four frames before and five frames before the decoding target frame.

A frame area M4 of the frame memory M4
a, a frame area M4b, a frame area M4c, and
The frame area M4d stores image data of reference frames 6 frames before, 7 frames before, 8 frames before, and 9 frames before the decoding target frame.

Here, the image data is stored in the frame memory M1 in a form in which image data input from outside the image data storage device is stored without compression.

The storage form of the image data in the frame memory M2 is a form in which the image data is reversibly compression-coded by the compression circuit A1 and stored.

The storage form of the image data in the frame memory M3 is a form in which the image data is irreversibly compressed and encoded by the compression circuit A2 and stored.

The form of storage of image data in the frame memory M4 is a form in which image data is irreversibly compressed and encoded by the compression circuit A3 and stored.

However, the compression circuit A3 performs irreversible compression encoding at a higher compression ratio than the compression circuit A2.

As described above, the frame memories M2 to M4
Each stores the compressed image data.

Therefore, in each of the frame memories M2 to M4, the storage capacity per frame can be reduced as compared with the frame memory M1 which stores image data without compression.

[0302] Each of the frame memories M3 and M4 stores lossy compression-coded image data.

[0303] Therefore, in each of the frame memories M3 and M4, the storage capacity per frame can be reduced as compared with the frame memory M2 which stores image data by lossless compression encoding.

[0304] The frame memory M4 compresses and stores the image data by the compression circuit A3 having a higher compression ratio than the compression circuit A2.

Therefore, in the frame memory M4, the storage capacity per frame can be reduced as compared with the frame memory M3 in which image data is compressed by the compression circuit A2 and stored.

As described above, in the image data storage means 2, a plurality of frame memories M1 to M4 are provided, and the storage area per frame is reduced stepwise.

Next, the reading of image data from the image data storage means 2 will be described.

At the time of reading image data from the image data storage means 2, a macro block to be read is specified to the control circuit 42 by the control signal S.

Then, the control circuit 42 reads out the specified macro block from the memory control circuits MC 1 to MC 4 which control the frame memories M 1 to M 4 storing the specified macro block. To instruct.

If the macro block to be read is stored in the frame memory M1, the image data of the macro block to be read is not compressed and coded, so that it is directly output to the outside of the image data storage device.

When a macro block to be read is stored in the frame memories M2 to M4, it is decoded by the corresponding decompression circuits B1 to B3 and output to the outside of the image data storage device.

The memory control means 41 can arbitrarily output the image data of the frame stored in the image data storage means 2 to the outside in macroblock units, similarly to the memory control means 41 in the first embodiment. , First storage-related information (see FIG. 2) and second storage-related information (FIG. 3).
See).

As described above, the process of reading image data from the image data storage device to the outside (decompression decoding process by the image data decompression means 3 and output to the outside) is performed on a macroblock basis.

Similarly, processing for writing image data input from outside the image data storage device (input from outside,
And compression encoding processing by the image data compression means 1)
Is also performed on a macroblock basis.

Address control in each of the frame memories M1 to M4 when performing processing in units of macroblocks is performed by the corresponding memory control circuits MC1 to MC4.

Next, the operation of updating the image data stored in the frame memories M1 to M4 will be described.

FIG. 7 is an explanatory diagram of the operation at the time of updating the image data stored in the frame memories M1 to M4.

In FIG. 7, state 1, state 2-1, state 2
2, state 2-3, and state 3, the frame areas M1a, M1b, M2a,
M2b, M3a, M3b, and M4a to M4d indicate what number frame is stored. It is also assumed that the smaller the number is, the earlier the frame (past frame).

The state 1 indicates the states of the frame memories M1 to M4 at the time when the decoding of the s-th frame is completed. “S” is an integer of 10 or more.

That is, in the state 1, the frame memory M1
The s-th frame is stored in the frame area M1a, the s-1-th frame is stored in the frame area M1b, and the s-2-th frame is stored in the frame area M2a of the frame memory M2. , Frame area M
2b stores the s-3rd frame, the s-4th frame is stored in the frame area M3a of the frame memory M3, and the s-5th frame is stored in the frame area M3b. The s-6th frame is stored in the frame area M4a of the frame memory M4,
The s-7th frame is stored in the frame area M4b, the s-8th frame is stored in the frame area M4c, and the s-9th frame is stored in the frame area M4d.

[0321] In state 1, the s-th frame is
This is the frame to be decoded. The (s-1) th frame is a reference frame one frame before the current frame to be decoded, and the (s-2) th frame is 2 frames before the current frame to be decoded.
The reference frame before the frame, the s−3 th frame is a reference frame three frames before the decoding target frame, the s−4 th frame is a reference frame four frames before the decoding target frame, The s−5th frame is a reference frame 5 frames before the decoding target frame, the s−6th frame is a reference frame 6 frames before the decoding target frame, and s−7.
The 番 目 th frame is a reference frame 7 frames before the decoding target frame, the s−8th frame is a reference frame 8 frames before the decoding target frame,
The s-ninth frame is a reference frame nine frames before the frame to be decoded.

The reference frame must be updated before proceeding to the decoding process of the s + 1-th frame which is the next frame.

When the reference frame is updated, the image data of the newly stored reference frame is overwritten in the frame area where the temporally oldest reference frame is stored in each of the frame memories M1 to M4. This point will be described in detail.

[0324] The state 2-1 is a frame memory M1 for updating the reference frame stored in the frame memory M4 (state 1) for storing the reference frame 6 to 9 frames before.
To M4.

The operation for updating the reference frame stored in the frame memory M4 will be described with reference to state 2-1.

The frame areas M4a to M4c storing the s-6, s-7, and s-8th reference frames are represented by s
The stored reference frame is held as it is as the reference frame 7 to 9 frames before when decoding the + 1st frame.

On the other hand, the image data of the s−5th reference frame, which is the reference frame 5 frames before in the state 1, is read from the frame area M3b, and the decompression circuit B
2, and are recompressed by the compression circuit A3.

Then, in the frame area M4d storing the s-9th reference frame which is not necessary as the reference frame when decoding the s + 1th frame, the recompressed image data of the s-5th reference frame is stored. Written.

S-5 written in frame area M4d
The image data of the reference frame becomes the reference frame six frames before when the s + 1-th frame is decoded. State 2-2 indicates the state of the frame memories M1 to M4 when the reference frame stored in the frame memory M3 (state 1) storing the reference frame four or five frames before is updated.

The operation for updating the reference frame stored in the frame memory M3 will be described with reference to state 2-2.

[0331] The frame area M3a for storing the s-4th reference frame holds the stored reference frame as it is as the reference frame 5 frames before when the s + 1th frame is decoded.

On the other hand, the image data of the s-third reference frame, which is the reference frame three frames before in state 1, is read from the frame area M2b,
1 and is recompressed by the compression circuit A2.

Then, in the state 1, the recompressed image data of the s-3rd reference frame is written in the frame area M3b storing the s-5th reference frame.

S-3 written in frame area M3b
The image data of the reference frame becomes the reference frame four frames before when the s + 1-th frame is decoded.

The state 2-3 is a frame memory M1 for updating the reference frame stored in the frame memory M2 (state 1) for storing the reference frame a few frames before.
To M4.

The operation of updating the reference frame stored in the frame memory M2 will be described with reference to state 2-3.

The frame area M2a for storing the s−2th reference frame holds the stored reference frame as it is as the reference frame three frames before when decoding the s + 1th frame.

On the other hand, the image data of the (s−1) th reference frame, which is the reference frame one frame before in the state 1, is read from the frame area M1b, and the compression circuit A
Compressed by one.

Then, in the state 1, the compressed image data of the (s−1) th reference frame is written into the frame area M2b in which the (s−3) th reference frame is stored.

S-1 written in frame area M2b
The image data of the reference frame becomes the reference frame two frames before when the s + 1-th frame is decoded.

State 3 represents the state of the frame memories M1 to M4 at the start of decoding the s + 1-th frame.

The operation for updating the reference frame stored in the frame memory M1 will be described with reference to state 3.

The frame area M1a for storing the s-th frame holds the stored frame as it is as the reference frame one frame before when decoding the s + 1-th frame.

As described above, the frame memories M1 to M1
The reference frame stored in M4 is updated.

Since data can be input and output in units of macroblocks, the reference frames in each of the frame memories M1 to M4 can be updated in parallel (parallel processing is possible). Therefore, the processing time can be reduced.

As described above, in the present embodiment,
The frame memories M2 to M4 store image data that has been compression-encoded.

Therefore, each of the frame memories M2 to M4 can reduce the storage capacity per frame as compared with the frame memory M1 which stores image data without compression.

The frame memories M3 and M4 store image data that has been subjected to lossy compression encoding.

Therefore, in each of the frame memories M3 and M4, the storage capacity can be reduced as compared with the frame memory M2 for storing image data subjected to lossless compression encoding.

Further, the frame memory M4 compresses the image data by a compression circuit A3 having a higher compression ratio than the compression circuit A2 and stores the image data.

Therefore, in the frame memory M4, the storage capacity per frame can be reduced as compared with the frame memory M3 in which image data is compressed by the compression circuit A2 and stored.

As described above, in the present embodiment, the storage area allocated to one frame becomes smaller as the time becomes past with reference to the decoding target frame, so that the storage capacity of the image data storage means 2 is reduced. Can be greatly reduced.

When irreversible compression encoding is performed, image data deteriorates during decoding.

[0354] Therefore, when irreversibly compressed image data is used as a reference frame, the image quality of the decoded image is degraded, and errors are accumulated until an intra frame is reproduced thereafter.

However, when considering the correlation between frames in a moving picture, the correlation tends to be higher as the time is closer, and the correlation is lower as the distance is longer. The percentage that is high.

That is, based on the frame to be decoded,
Most often, the reference frame one frame before is used, then the reference frame a few frames before, the next four, five frames before, and then the reference frame six to nine frames before.

As described above, the frequency of using the reference frame 4 to 9 frames before the lossy compression encoding is performed is low.

Accordingly, deterioration of the image quality of the decoded image due to the use of the reference frame subjected to the lossy compression encoding is avoided as much as possible.

When the compressed image data is used as a reference frame, it must be expanded by expansion circuits B1 to B3.

Therefore, at the time of decoding processing by the moving picture decoding apparatus, extra time is required for the expansion processing by the expansion circuits B1 to B3.

However, since the image data of the reference frame immediately before the most frequently used frame is stored without compression, no time is required for the decompression process.

Therefore, in the present embodiment, the time required for the decompression processing in the decoding processing by the video decoding apparatus can be greatly reduced.

As described above, this embodiment focuses on the tendency that the frequency of use differs depending on the temporal position of the reference frame.

[0364] In the frame memories M1 to M4 of the image data storage means 2, a large number of storage areas are allocated to reference frames which are temporally close to the frame to be decoded and which are frequently used, and reference frames which are temporally distant and infrequently used. The allocation of storage areas to frames is reduced gradually. In this case, the most frequently used reference frame is stored without compression.

By doing so, it is possible to reduce the storage capacity of the image data storage means 2 while suppressing an increase in decoding processing time due to an increase in compression processing and decompression processing.

[0366] In the above description, the image data storage device 80 in the moving picture decoding device shown in Fig. 5 has been described.
Image data storage device 8 in the moving image encoding device of FIG.
0 has the same configuration as the image data storage device shown in FIG. 6, and has the same operation and effect.

In the present embodiment, the number of reference frames is nine. However, the number of reference frames is not limited to this, and may be any number.

In this embodiment, each of the frame memories M1 to M3 has two frame areas, and the frame memory M4 has four frame areas.

However, the number of frame areas per one frame memory is not limited to this, and an arbitrary number of frame areas can be provided.

In the present embodiment, there are four types of storage modes in the image data storage means 2, and four frame memories M1 to M4 are provided.

However, the type of storage mode in the image data storage means 2 is not limited to this, and any type of storage mode can be adopted and an arbitrary number of frame memories can be provided.

That is, the number of frame memories can be changed by appropriately inserting or deleting compression circuits and decompression circuits according to the type of storage mode.

Also, in the present embodiment, the reference frame immediately before the frame to be encoded is stored without compression, but may be stored after compression.

However, in consideration of the frequency of use, it is preferable to store the data without compression.

In this embodiment, lossless compression and irreversible compression are adopted as the compression method by the image data compression means 1. However, the compression ratios of the respective compression circuits are different, and only lossless compression or irreversible compression is employed. Compression alone can also be employed.

In this embodiment, the image data compression means 1 has one compression circuit for performing lossless compression and two compression circuits for performing irreversible compression.

However, the number of compression circuits for performing lossless compression and the number of compression circuits for performing irreversible compression are not limited to these.

In the present embodiment, the data processing unit for the accumulation processing in the frame memory Mj and the output processing from the frame memory Mj has been described as a macroblock unit of 16 × 16 pixels.

However, the data processing unit is not limited to the macro block unit. For example, 8 × 8 pixels,
The block size serving as a data processing unit, such as 8 × 16 pixels, can be arbitrarily determined.

Also, not only the image data storage device of FIG. 6 but also the image data storage device of FIG. 1 is used as the image data storage device 80 of the moving image encoding device of FIG. 4 and the moving image decoding device of FIG. it can.

In the above description, the moving picture compression / decompression system in which the moving picture coding apparatus shown in FIG. 4 and the moving picture decoding apparatus shown in FIG. 5 are combined has been described. However, it is not always necessary to use both in combination. 4 and a general moving image decoding apparatus, and a general moving image encoding apparatus and a moving image decoding apparatus of FIG. , Can also be used in combination.

As in the first embodiment, the image data storage device shown in FIG. 6 can be used alone.

In this case, for example, it can be used to store a still image. Then, an appropriate storage mode can be selected in consideration of the image quality of the image data, the number of stored images, and the like according to the purpose of use of the image data. Therefore, also in this case, the storage capacity can be reduced while suppressing an increase in the processing amount.

In the image data storage device shown in FIG. 6, the compression ratios of the compression circuits A1 to A3 are different from each other.

However, the present invention is not limited to this.
For example, the compression schemes of the compression circuits A1 to A3 may be different from each other. In this case, the compression ratios of the compression circuits A1 to A3 may be the same as each other or may be different.

[0386] This allows the user to store the image data without compression, or to store the image data after compression, and when compressing and storing the image data, which compression method should be used to store the image data. , Can be arbitrarily selected in frame units.

As a result, the storage capacity can be reduced while improving the convenience for the user.

(Embodiment 3) The video compression / decompression system according to Embodiment 3 of the present invention includes a video encoding device and a video decoding device.

[0389] The overall configuration of this video coding apparatus is shown in FIG.
Is the same as the overall configuration of the moving picture coding apparatus.

Accordingly, in the third embodiment, the moving picture coding apparatus of FIG. 4 will be described as the moving picture coding apparatus of the third embodiment.

[0391] The overall configuration of this video decoding apparatus is shown in FIG.
This is the same as the overall configuration of the video decoding device.

Therefore, in the third embodiment, the moving picture decoding apparatus of FIG. 5 will be described as the moving picture decoding apparatus of the third embodiment.

A description will be given of an image data storage device 80 of the moving image decoding device in FIG.

In the image data storage device 80 of the moving picture decoding apparatus of FIG. 5 according to the third embodiment, the compression method by the image data compression means 1 of FIG. 6 is changed to a compression method by thinning, and the image data decompression means of FIG. 3 is an expansion method based on linear interpolation. Hereinafter, a specific description will be given.

FIG. 8 is a block diagram of the image data storage device 80 of FIG. 5 according to the third embodiment.

In FIG. 8, the same parts as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

As shown in FIG. 8, this image data storage device comprises an image data compression means 1, an image data storage means 2,
An image data decompression unit 3 and a control unit 4 are provided.

The image data compression means 1 includes a thinning circuit C
1, C2 and C3. Note that the thinning circuits C1, C2,
C3 corresponds to the compression means A1, A2, A3 in FIG. 6, respectively.

The image data decompression means 3 includes an interpolation circuit 31. Note that the interpolation circuit 31 includes the decompression circuits B1 to B
Equivalent to 3.

The configurations of the image data storage unit 2 and the control unit 4 are the same as those of the image data storage unit 2 and the control unit 4 in FIG. 6, respectively.

Next, the operation of the image data storage device of FIG. 8 will be described. The operation of the image data storage device of FIG.
Except for the compression and decompression processing, the operation is the same as that of the image data storage device in FIG. Therefore, the second embodiment will be described below.
The following description focuses on the differences.

A thinning process by the thinning circuits C1 to C3,
The interpolation processing by the interpolation circuit 31 will be described. First, the thinning process will be described.

FIG. 9 is an explanatory diagram of the thinning process performed in the vertical direction. FIG. 9A is a view showing an example of image data before thinning, and FIG. 9B is a view showing an example of image data after thinning.

In FIG. 9, each of the white circle and the black circle represents one pixel data.

As shown in FIG. 9A, the image data is
An 8 × 8 pixel block 200 will be described in which a vertical thinning process is performed on this pixel block.

[0406] In this case, the pixel data represented by the black circle is removed to execute the thinning process in the vertical direction.

As a result, as shown in FIG. 9B, it is possible to obtain a pixel block 210 in which the data amount is reduced by half in the vertical direction as compared with the pixel block 200.

FIG. 10 is an explanatory diagram of the thinning process performed in the horizontal direction. FIG. 10A is a view showing an example of image data before thinning, and FIG. 10B is a view showing an example of image data after thinning.

In FIG. 10, each of the white circle and the black circle represents one pixel data.

As shown in FIG. 10A, a case where the image data is a pixel block 300 of 8 × 8 pixels, and a thinning process is performed on this pixel block in the horizontal direction will be described.

[0411] In this case, by removing the pixel data represented by the black circle, the thinning process in the horizontal direction is executed.

As a result, as shown in FIG. 10B, it is possible to obtain a pixel block 310 in which the data amount is reduced by half in the horizontal direction as compared with the pixel block 300.

Next, the interpolation processing will be described. The interpolation process is a process that is the reverse of the thinning process.

That is, the pixel block 210 shown in FIG.
The pixel data corresponding to the pixel data of the black circle in the pixel block 200 is obtained by linear interpolation using the pixel data vertically adjacent to the pixel block 200, and the obtained pixel data is inserted into the corresponding position to perform the vertical interpolation processing. Is executed.

Also, the pixel block 310 shown in FIG.
The horizontal interpolation process is performed by obtaining pixel data corresponding to black circle pixel data in the pixel block 300 by linear interpolation using pixel data adjacent to the right and left in the pixel block 300 and inserting the obtained pixel data into a corresponding position. Is executed.

Next, the thinning circuits C1 to C3 in FIG.
And the operation of the interpolation circuit 31 are stored in the frame memories M1 to M4.
This will be specifically described in relation to the above.

FIG. 11 is a conceptual diagram of image data stored in the frame memories M1 to M4. FIG. 11 (a)
A conceptual diagram of image data stored in the frame memory M1,
FIG. 11B is a conceptual diagram of image data stored in the frame memory M2, and FIG.
11D is a conceptual diagram of image data stored in the frame memory M4. FIG. 11D is a conceptual diagram of image data stored in the frame memory M4.

The storage format of the frame memory M1 is a format in which image data is stored without being compressed.
As shown in (a), each of the frame regions M1a and M1b of the frame memory M1 stores a pixel block 400 of S × T pixels on which no thinning process is performed.

Therefore, image data is directly input to the frame memory M1 from outside the image data storage device.
Then, it is stored. Here, one frame is
It is assumed that it is composed of S × T pixels.

The thinning circuits C1 and C3 are circuits for performing thinning processing in the vertical direction, and the thinning circuit C2 is a circuit for performing thinning processing in the horizontal direction.

Therefore, as shown in FIG. 11 (b), each of the frame areas M2a and M2b of the frame memory M2 is thinned in the vertical direction by the thinning circuit C1 and has a smaller data amount than the pixel block 400. Is 1/2 in the vertical direction
Is stored.

As shown in FIG. 11 (c), each of the frame areas M3a and M3b of the frame memory M3 is thinned in the horizontal direction by the thinning circuit C2, and compared with the pixel block 410, Is １ ／ in the horizontal direction
Is stored.

As shown in FIG. 11D, each of the frame areas M4a to M4d of the frame memory M4 is thinned in the vertical direction by the thinning circuit C3, and the data amount is smaller than that of the pixel block 420. Is 1/2 in the vertical direction
Is stored.

[0424] The interpolation circuit 31 repeats the necessary number of interpolation processes to restore the pixels thinned out by the thinning process.

[0425] In the present embodiment, in the process of updating the reference frame stored in the image data storage means 2,
The second embodiment differs from the second embodiment when the reference frame is moved by changing the storage mode from the frame memory M2 to the frame memory M3, and when the reference frame is transferred by changing the storage mode from the frame memory M3 to the frame memory M4. hand,
The compression processing can be directly performed by the thinning circuit C2 or the thinning circuit C3 without passing through the decompression circuit.
In addition, the thinning process is a relatively simple process.

[0426] Therefore, it is possible to update the reference frame stored in the image data storage means 2 at high speed.

In this embodiment, the process of reading image data from the image data storage device to the outside (interpolation by the interpolation circuit 31 of the image data decompression means 3 and output to the outside) is performed with an arbitrary block size. be able to.

Also, the processing of writing image data input from outside the image data storage device (input from the outside and the thinning processing by the thinning circuits C1 to C3 of the image data compression means 1) can be performed with an arbitrary block size. It can be carried out.

In this embodiment, the image data stored in the frame memories M2 to M4 is stored in the thinning circuit C1.
C3 is image data compressed by the thinning process by C3.

For this reason, the expansion processing of the image data stored in the frame memories M2 to M4 can be performed by linear interpolation.

Therefore, the three frame memories M2 to M4
Thus, the interpolation circuit 31 that performs linear interpolation can be shared, and the circuit size can be reduced.

Also, in the present embodiment, similar to the second embodiment, each reference frame is stored in an appropriate storage mode in consideration of the frequency of use.

As a result, in this embodiment, as in the second embodiment, the storage capacity can be reduced while suppressing an increase in the processing amount.

Now, the image data storage device 80 in the moving picture decoding apparatus of FIG. 5 has been described above, but the image data storage apparatus 80 in the moving picture coding apparatus of FIG. It has the same configuration as the data storage device, and has the same operation and effect.

In this embodiment, the thinning-out process is performed by thinning out the pixel data for each pixel. However, the interval between the pixels to be thinned out is not limited to this.

In the present embodiment, the thinning is performed in the order of the vertical direction, the horizontal direction, and the vertical direction. However, the order of the thinning direction is not limited to this.

In the present embodiment, the thinning circuit C1
Then, only in the vertical direction, in the thinning circuit C2, only in the horizontal direction,
In the thinning circuit C3, the thinning direction by each of the thinning circuits C1 to C3 is set to one direction, such as only in the vertical direction, but it is also possible to perform thinning in the horizontal direction and the vertical direction at once.

In this embodiment, the interpolation circuit 31
Performed linear interpolation using vertically adjacent pixel data or linear interpolation using left and right adjacent pixel data.

However, the present invention is not limited to such linear interpolation using two pixels, but includes four neighboring pixels and eight neighboring pixels.
An interpolation method using an arbitrary number of pixels, such as pixels, can also be adopted.

Also, as the image data storage device 80 of the moving image encoding device of FIG. 4 and the moving image decoding device of FIG. 5, not only the image data storage device of FIG. 8 but also the image data storage device of FIG. it can.

Also, in the above description, the moving picture compression / decompression system combining the moving picture coding apparatus of FIG. 4 and the moving picture decoding apparatus of FIG. 5 has been described. However, it is not always necessary to use both in combination. 4 and a general moving image decoding apparatus, and a general moving image encoding apparatus and a moving image decoding apparatus of FIG. , Can also be used in combination.

Also, as in the first embodiment, the image data storage device of FIG. 8 can be used alone.

In this case, for example, it can be used to store a still image. Then, an appropriate storage mode can be selected in consideration of the image quality of the image data, the number of stored images, and the like according to the purpose of use of the image data. Therefore, also in this case, the storage capacity can be reduced while suppressing an increase in the processing amount.

(Embodiment 4) A moving picture compression / decompression system according to Embodiment 4 of the present invention includes a moving picture encoding apparatus and a moving picture decoding apparatus.

[0445] The overall configuration of this moving picture coding apparatus is shown in FIG.
Is the same as the overall configuration of the moving picture coding apparatus.

Therefore, in the fourth embodiment, the moving picture coding apparatus of FIG. 4 will be described as the moving picture coding apparatus of the fourth embodiment.

[0447] The overall configuration of this video decoding apparatus is shown in FIG.
This is the same as the overall configuration of the video decoding device.

Therefore, in the fourth embodiment, the moving picture decoding apparatus in FIG. 5 will be described as the moving picture decoding apparatus in the fourth embodiment.

[0449] An image data storage device 80 of the moving picture decoding device shown in Fig. 5 in Embodiment 4 will be described.

In the image data storage device 80 of the moving picture decoding apparatus of FIG. 5 according to the fourth embodiment, the compression method by the image data compression means 1 of FIG. 6 is changed to a compression method by wavelet transform, and the image data decompression of FIG. The expansion method by means 3 is an expansion method by inverse wavelet transform. Hereinafter, a specific description will be given.

FIG. 12 is a block diagram of the image data storage device 80 of FIG. 5 in the fourth embodiment.

In FIG. 12, the same parts as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

As shown in FIG. 12, this image data storage device includes an image data compression unit 1, an image data storage unit 2, an image data decompression unit 3, and a control unit 4.

The image data compression means 1 comprises wavelet transform circuits D1, D2 and data reduction circuits E1, E
2, E3.

The wavelet transform circuit D1 and the data reduction circuit E1 correspond to the compression means A1 in FIG. 6, and the data reduction circuit E2 corresponds to the compression means A2 in FIG. E3 is
This corresponds to the compression means A3 in FIG.

The image data decompression means 3 includes an inverse wavelet transform circuit 32 and a data interpolation circuit 33.

Note that the inverse wavelet transform circuit 32 and the data interpolation circuit 33 correspond to the decompression circuits B1 to B3 in FIG.
Is equivalent to

The configurations of the image data storage unit 2 and the control unit 4 are the same as those of the image data storage unit 2 and the control unit 4 of FIG.

Next, the operation of the image data storage device shown in FIG. 12 will be described. The operation of the image data storage device of FIG. 12 is the same as the operation of the image data storage device of FIG. 6 except for the compression and decompression processing. Therefore, the following description focuses on differences from the second embodiment.

The wavelet transform by the wavelet transform circuits D1 and D2 and the inverse wavelet transform by the inverse wavelet transform circuit 32 will be described.
First, the wavelet transform will be described.

FIG. 13 is an explanatory diagram of the wavelet transform. FIG. 13A is a conceptual diagram of image data before wavelet transform, and FIG. 13B is a conceptual diagram of image data after wavelet transform.

The wavelet transform is a filtering process that divides image data into low frequency region components and high frequency region components.

Since the image data is two-dimensional data, in one wavelet transform process, two filtering processes are performed in the vertical and horizontal directions.

The pixel block 500 shown in FIG.
Are image data to be subjected to wavelet transform.

When the wavelet transform is applied to the pixel block 500, four blocks 510a, 510b, 510c, and 510d have four blocks as shown in FIG.
An equally divided block 510 can be obtained.

The block 510a is an LL component block composed of image data of low frequency region components in both the horizontal and vertical directions.

The block 510b is composed of image data of low frequency region components in the horizontal direction and high frequency region components in the vertical direction.
This is an H component block.

[0468] The block 510c is composed of image data of high frequency region components in the horizontal direction and low frequency region components in the vertical direction.
This is an L component block.

[0469] The block 510d is an HH component block composed of image data of high frequency region components in both the horizontal and vertical directions.

Next, the inverse wavelet transform will be described. The inverse wavelet transform is an inverse filter process of the wavelet transform process, and is a process of converting the block 510 into the pixel block 500.

[0471] For the reduced block among the four blocks 510a to 510d constituting the block 510, the data interpolation circuit 33 interpolates "0" into all of the wavelet transform coefficients of the reduced block.
After that, the inverse wavelet transform circuit 32 performs an inverse wavelet transform process.

Next, the operation of the image data compression means 1 and the image data decompression means 3 of FIG. 12 will be specifically described in relation to the frame memories M1 to M4.

FIG. 14 is a conceptual diagram of image data stored in the frame memories M1 to M4. FIG. 14 (a)
A conceptual diagram of image data stored in the frame memory M1,
FIG. 14B is a conceptual diagram of image data stored in the frame memory M2, and FIG.
14D is a conceptual diagram of image data stored in the frame memory M4. FIG. 14D is a conceptual diagram of image data stored in the frame memory M4.

The storage format of the frame memory M1 is a format in which image data is stored without compression.
As shown in (a), each of the frame areas M1a and M1b of the frame memory M1 stores a pixel block 600 of S × T pixels on which no wavelet transform is performed.

Therefore, image data is directly input to the frame memory M1 from outside the image data storage device.
Then, it is stored. Here, one frame is
It is assumed that it is composed of S × T pixels.

The wavelet transform circuit D1 performs a wavelet transform on the pixel block 600 read out from the frame memory M1, and performs LL component block, LH component block, HL component block, and HH
Block consisting of component blocks (see FIG. 13B)
Generate

Then, the data reduction circuit E1 deletes the HL component block and the HH component block from the block, and outputs a block composed of the LL component block and the LH component block to the frame memory M2. .

Therefore, as shown in FIG. 14B, a block 610 composed of an LL component block and an LH component block is stored in each of the frame areas M2a and M2b of the frame memory M2.

[0479] The data amount of this block 610 is 1/2 that of the pixel block 600.

The data reduction circuit E2 deletes the LH component block from the block 610 read from the frame memory M2, and outputs a block consisting of only the LL component block to the frame memory M3.

Therefore, as shown in FIG. 14C, a block 620 consisting of only LL component blocks is stored in each of the frame areas M3a and M3b of the frame memory M3.

[0482] The data amount of this block 620 is 1/2 that of the block 610.

The wavelet transform circuit D2 performs a wavelet transform on the block 620 read from the frame memory M3, and performs LL component blocks and L
A block including an H component block, an HL component block, and an HH component block is generated.

Here, a block composed of only the LL component block is subjected to wavelet transform, and the generated LL component is expressed as an LL_LL component, and the generated LH component is expressed as an LL_LH component. The HL component is expressed as an LL_HL component, and the generated HH component is expressed as an LL_HH component.

Then, data reduction circuit E3 sets LL
_LL component block, LL_LH component block, LL_
From the block composed of the HL component block and the LL_HH component block, the LL_HL component block and the LL
The _HH component block is deleted, and a block including the LL_LL component block and the LL_LH component block is output to the frame memory M4.

Therefore, as shown in FIG. 14D, a block 630 including an LL_LL component block and an LL_LH component block is stored in each of the frame areas M4a to M4d of the frame memory M4.

[0487] The data amount of this block 630 is 1/2 that of the block 620.

Now, when expanding the image data stored in the frame memories M2 to M4, the data interpolation circuit 33
Interpolates the wavelet transform coefficients of the blocks deleted by the data reduction circuits E1 to E3 with "0".

Then, the inverse wavelet transform circuit 32
Performs inverse filter processing on a block including a block that has not been deleted and a block obtained by interpolation to restore the original pixel block.

In the present embodiment, in the process of updating the reference frame stored in the image data storage unit 2,
When transferring the reference frame from the frame memory M2 to the frame memory M3 by changing the storage mode, the compression processing is performed by the data reduction circuit E2 without passing through the inverse wavelet transform circuit 32 that performs the expansion processing.

In the process of updating the reference frame stored in the image data storage means 2, the frame memory M3
When the reference frame is transferred by changing the storage mode from the frame memory M4 to the frame memory M4, the wavelet transform circuit D2 does not pass through the inverse wavelet transform circuit 32 for performing the decompression process
And a compression process by the data reduction circuit E3.

As described above, since the signal does not pass through the inverse wavelet transform circuit 32 for performing the decompression process, the reference frame stored in the image data storage means 2 can be updated at a high speed.

In this embodiment, the image data stored in the frame memories M2 to M4 is image data compressed by the wavelet transform circuits D1 and D2 and the data reduction circuits E1 to E3.

Therefore, the expansion processing of the image data stored in the frame memories M2 to M4 can be performed by interpolation and inverse wavelet transform.

Therefore, the three frame memories M2 to M4
Thus, the data interpolation circuit 33 for performing the interpolation and the inverse wavelet transform circuit 32 for performing the inverse wavelet transform can be shared, and the circuit scale can be reduced.

Also, for human vision, low frequency region components are more important than high frequency region components of image data.
Therefore, when the image data is compressed by the image data compressing means 1, the image data is deleted from the high frequency region components.

In this embodiment, the data reduction circuit E1
Deletes the HL component block and the HH component block,
The data reduction circuit E2 deletes the LH component block, and the data reduction circuit E3 generates the LL_HL component block and LL
The _HH component block has been deleted.

[0498] By doing so, a low-frequency region component that is important for human vision remains, and deterioration of the image quality of an image decoded using the decompressed image data as a reference frame can be reduced.

Also, in the present embodiment, similar to the second embodiment, each reference frame is stored in an appropriate storage mode in consideration of the frequency of use.

As a result, in this embodiment, as in Embodiment 2, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

[0501] In this embodiment, for convenience of explanation, the pixel block 600 shown in Fig. 14A has been described as being one frame of image data.

However, the size of a pixel block in one wavelet transform process is not limited to this.

A pixel block of one frame is divided into a plurality of pixel blocks, a wavelet transform process is performed on each of the divided pixel blocks, and frequency domain components are collected to form image data for one frame. it can. This will be described with a specific example with reference to FIG.

[0504] A pixel block of one frame is, for example, 4 pixels.
Equally divided, a quarter pixel block is used as a data processing unit.

Then, this 1/4 pixel block is represented by S
× T pixels. Then, if you do not compress
4 (a), four 1/4 pixel blocks 600 are collected into one frame of image data, and the one frame of image data is stored in the frame area M of the frame memory M1.
1a and M1b.

[0506] The wavelet transform circuit D1 is a 1/4 pixel block 600 read from the frame memory M1.
Is subjected to a wavelet transform, and the LL component block, LH component block, HL component block, and HH
Block consisting of component blocks (see FIG. 13B)
Generate

Then, the data reduction circuit E1 deletes the HL component block and the HH component block from the block, and outputs a block composed of the LL component block and the LH component block to the frame memory M2. .

The LL component block and L
The block consisting of the H component block is
The four pixel blocks 600 are also generated and output to the frame memory M2.

Therefore, as shown in FIG.
Four blocks 610 each composed of a component block and an LH component block are collected into one frame of image data, and the one frame of image data is stored in each of the frame areas M2a and M2b of the frame memory M2. You.

[0510] The data reduction circuit E2 includes a frame memory M
Then, the LH component block is deleted from the block 610 read from the block No. 2, and a block consisting of only the LL component block is output to the frame memory M3.

[0511] Such a block consisting only of the LL component block is generated for the other three blocks 610, and is output to the frame memory M3.

[0512] Therefore, as shown in FIG.
Collect four blocks 620 consisting only of component blocks,
One frame of image data is stored in the frame area M3 of the frame memory M3.
a and M3b.

[0513] The wavelet transform circuit D2 performs a wavelet transform on the block 620 read from the frame memory M3, and performs LL_LL component blocks and L
A block including an L_LH component block, an LL_HL component block, and an LL_HH component block is generated.

[0514] The data reduction circuit E3 deletes the LL_HL component block and the LL_HH component block from the block composed of the LL_LL component block, the LL_LH component block, the LL_HL component block, and the LL_HH component block, and deletes the LL_LL component block and LL_L.
A block composed of H component blocks is stored in a frame memory M
Output to 4.

[0515] Such a block composed of the LL_LL component block and the LL_LH component block is also generated for the other three blocks 620, and is output to the frame memory M4.

Therefore, as shown in FIG. 14D, LL
Four blocks 630 each composed of an _LL component block and an LL_LH component block are collected into one frame of image data, and the one frame of image data is stored in each of the frame areas M4a to M4d of the frame memory M4.

[0517] In the above description, the image data storage device 80 in the moving picture decoding device in FIG. 5 has been described. However, the image data storage device 80 in the moving picture coding device in FIG. It has the same configuration as the data storage device, and has the same operation and effect.

[0518] As the image data storage device 80 of the video encoding device of Fig. 4 and the video decoding device of Fig. 5, not only the image data storage device of Fig. 12 but also the image data storage device of Fig. 1 are used. it can.

[0519] In the above description, the moving picture compression / decompression system in which the moving picture coding apparatus of FIG. 4 and the moving picture decoding apparatus of FIG. 5 are combined has been described. However, it is not always necessary to use both in combination. 4 and a general moving image decoding apparatus, and a general moving image encoding apparatus and a moving image decoding apparatus of FIG. , Can also be used in combination.

As in the first embodiment, the image data storage device shown in FIG. 12 can be used alone.

In this case, for example, it can be used to store a still image. Then, an appropriate storage mode can be selected in consideration of the image quality of the image data, the number of stored images, and the like according to the purpose of use of the image data. Therefore, also in this case, the storage capacity can be reduced while suppressing an increase in the processing amount.

(Embodiment 5) FIG. 15 is a block diagram of a moving picture compression / decompression system according to Embodiment 5 of the present invention. In FIG. 15, the same components as those in FIG. 4 or FIG. 5 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

As shown in FIG. 15, a moving picture coding apparatus 1000 of this moving picture compression / decompression system is obtained by adding a multiplexing circuit 1100 to the structure of the moving picture coding apparatus shown in FIG.

[0524] Further, the moving picture decoding apparatus 2000 of this moving picture compression / decompression system is obtained by adding a separating circuit 2100 to the structure of the moving picture decoding apparatus of FIG.

[0525] The image data storage device 80 of the moving image encoding device 1000 and the image data storage device 80 of the moving image decoding device 2000 are the same.

Next, the operation will be described focusing on the differences from FIGS. 4 and 5. The multiplexing circuit 1100 includes: moving image encoded data input from the variable length encoding circuit 40;
It multiplexes the information related to the compression of the reference frame input from the image data storage device 80, and sends out the multiplexed data to the communication path 1500.

Here, the information relating to the compression of the reference frame is the compression parameter (FIG. 2) used when the reference frame used for the encoding target frame is stored in the image data storage device 80 of the moving image encoding apparatus 1000. Reference).

[0528] Separation circuit 21 of video decoding apparatus 2000
00 inputs the multiplexed data transmitted by the multiplexing circuit 1100 from the communication path 1500.

The separation circuit 2100 separates the multiplexed data into coded video data and information related to the compression of the reference frame.

[0531] The separation circuit 2100 outputs the encoded video data to the variable length decoding circuit 110, and outputs information related to the compression of the reference frame to the image data storage device 80.

[0531] Then, the image data storage device 80 of the video decoding device 2000 performs compression and decompression of the reference frame using the information on the compression used in the video data storage device 80 of the video encoding device 1000.

[0532] For this reason, even when the image data storage device 80 of the moving picture decoding apparatus 2000 stores and decompresses the reference frame by irreversibly compressing it, the moving picture coding apparatus 1000 can be used.
, The reference frame used at the time of encoding and the reference frame used at the time of decoding by the video decoding device 2000 are the same.

[0533] Therefore, in the present embodiment, the moving picture encoding apparatus 1000 and the moving picture decoding apparatus 2000 prevent the deterioration of the picture quality due to the inconsistency of the image data of the reference frame between the moving picture decoding apparatus 2000 and the moving picture decoding apparatus. The storage capacity of the frame memory of the image data storage device 80 of the image encoding device 1000 and the moving image decoding device 2000 can be reduced.

[0534] The moving picture coding apparatus 1000 shown in FIG.
And image data storage device 8 of video decoding device 2000
As 0, not only the image data storage device in FIG. 6 but also the image data storage device in FIG. 1, FIG. 8, or FIG. 12 can be used.

[0535]

According to the image data storage device of the present invention, in the image data storage device for storing the image data of a plurality of frames, it is possible to select an appropriate storage mode for each frame in consideration of the frequency of use. In addition, depending on the purpose of use of the image data, the image quality of the image data,
An appropriate storage mode can be selected in consideration of the above.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

[0537] In the image data storage device according to the second aspect,
In an image data storage device that stores image data of a plurality of frames, a more appropriate storage mode can be selected for each frame in consideration of the frequency of use. In addition, depending on the purpose of use of the image data, the image quality of the image data,
A more appropriate storage mode can be selected in consideration of the above.

As a result, it is possible to more effectively reduce the storage capacity while suppressing an increase in the processing amount.

In the image data storage device according to the third aspect,
In an image data storage device that stores image data of a plurality of frames, a more appropriate storage mode can be selected, so that the storage capacity can be more effectively reduced in consideration of suppressing an increase in the processing amount. Can be.

[0540] In the image data storage device of the fourth aspect,
The storage capacity can be reduced while suppressing an increase in the processing amount.

In the image data storage device according to the fifth aspect,
Compression processing and decompression processing of image data can be performed at high speed.

In the case where a plurality of compression means are provided and a plurality of second storage means are provided correspondingly, image data stored in a certain second storage means
When the storage mode is changed and stored in another second storage unit, the compression process can be performed without performing the decompression process.

Therefore, the processing for storing the image data stored in a certain second storage means in another second storage means by changing the storage mode can be performed at high speed.

In the case where a plurality of compression means are provided and a plurality of second storage means are provided correspondingly, the image data decompression means can be shared by the plurality of second storage means. Therefore, the circuit scale can be reduced.

[0545] In the image data storage device of the sixth aspect,
In the case where a plurality of compression units are provided and a plurality of second storage units are provided correspondingly, the image data stored in a certain second storage unit may be changed in storage form to another one. When storing the data in the second storage means, the compression processing can be performed without performing the decompression processing.

Therefore, it is possible to change the storage form of the image data stored in a certain second storage means and to store the image data in another second storage means at high speed.

In the case where a plurality of compression means are provided and a plurality of second storage means are provided correspondingly, the image data decompression means can be shared by the plurality of second storage means. Therefore, the circuit scale can be reduced.

Also, since low-frequency components are more important to human vision than high-frequency components of image data, if they are deleted from high-frequency components at the time of compression by the compression means, human Low-frequency area components that are important for vision remain, and deterioration of the image quality of the image after image processing using the decompressed image data can be reduced.

In the image data storage device according to the seventh aspect,
The image data stored in the first storage unit and the second storage unit can be updated.

[0550] In the image data storage device according to the eighth aspect,
The image data stored in the first storage unit and the second storage unit can be updated.

Further, since the image data decompression means is not used in the update processing, the speed of the update processing can be increased.

In the image data storage device according to the ninth aspect,
Image data can be read from the first storage unit or the second storage unit that stores image data in frame units in block units of m × n pixels.

In the image data storage device according to the tenth aspect, the user can select whether to store the image data without compression, or to store the image data after compression. It is possible to arbitrarily select, in a frame unit, whether the data is compressed and stored by the method.

As a result, the storage capacity can be reduced while improving the convenience for the user.

In the encoding apparatus according to the eleventh aspect, when a plurality of frames can be used as reference frames for encoding, an appropriate storage mode is selected for each reference frame in consideration of the frequency of use. it can.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

In the encoding apparatus according to the twelfth aspect, when a plurality of frames can be used as reference frames for encoding, each reference frame is stored in an appropriate storage form in consideration of the frequency of use. Is done.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

In the encoding apparatus according to the thirteenth aspect, when a plurality of frames can be used as reference frames for encoding, a more appropriate storage mode is selected for each frame in consideration of the frequency of use. it can.

As a result, it is possible to more effectively reduce the storage capacity while suppressing an increase in the processing amount.

In the encoding apparatus according to the fourteenth aspect, when a plurality of frames can be used as reference frames for encoding, each reference frame is stored in a more appropriate storage form in consideration of the frequency of use. It is memorized.

As a result, it is possible to more effectively reduce the storage capacity while suppressing an increase in the processing amount.

In the decoding device according to the fifteenth aspect, when a plurality of frames can be used as reference frames for decoding, an appropriate storage mode considering the frequency of use is selected for each reference frame. it can.

As a result, it is possible to reduce the storage capacity while suppressing an increase in the processing amount.

In the decoding device according to the present invention, when a plurality of frames can be used as reference frames for decoding, each reference frame is stored in an appropriate storage form in consideration of the frequency of use. Is done.

[0566] As a result, the storage capacity can be reduced while suppressing an increase in the processing amount.

In the decoding device according to the seventeenth aspect, when a plurality of frames can be used as reference frames for decoding, a more appropriate storage mode is selected for each frame in consideration of the frequency of use. it can.

As a result, it is possible to more effectively reduce the storage capacity while suppressing an increase in the processing amount.

In the decoding apparatus according to the eighteenth aspect, when a plurality of frames can be used as reference frames for decoding, each of the reference frames is stored in a more appropriate storage form in consideration of the frequency of use. It is memorized.

As a result, the storage capacity can be more effectively reduced while suppressing an increase in the processing amount.

In the compression / decompression system according to claim 19,
In the image data storage device of the decoding device, even when the reference frame is irreversibly compressed and stored and decompressed, the reference frame is the same in the encoding device and the decoding device.

As a result, while preventing the image quality from being deteriorated due to the inconsistency of the image data of the reference frame between the encoding device and the decoding device, the image data storage devices of the encoding device and the decoding device can be prevented. The storage capacity can be reduced.

In the compression / decompression system according to the twentieth aspect,
In the image data storage device of the decoding device, even when the reference frame is irreversibly compressed and stored and decompressed, the reference frame is the same in the encoding device and the decoding device.

As a result, while preventing the image quality from being deteriorated due to the inconsistency of the image data of the reference frame between the encoding device and the decoding device, the image data storage devices of the encoding device and the decoding device can be prevented. The storage capacity can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image data storage device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the first storage-related information.

FIG. 3 is an explanatory diagram of the second storage-related information.

FIG. 4 is a block diagram of a video encoding device of a video compression / decompression system according to Embodiment 2 of the present invention.

FIG. 5 is a block diagram of a moving image decoding device.

FIG. 6 is a block diagram of an image data storage device of the moving image decoding device.

FIG. 7 is an explanatory diagram of an update process in the image data storage device.

FIG. 8 is a block diagram of an image data storage device of a video decoding device of a video compression / decompression system according to Embodiment 3 of the present invention.

9A is a conceptual diagram of image data before thinning in the same vertical direction, and FIG. 9B is a conceptual diagram of image data after thinning in the same vertical direction.

10A is a conceptual diagram of image data before thinning in the horizontal direction, and FIG. 10B is a conceptual diagram of image data after thinning in the horizontal direction.

11A is a conceptual diagram of image data stored in the frame memory M1, FIG. 11B is a conceptual diagram of image data stored in the frame memory M2, and FIG. 11C is a conceptual diagram of image data stored in the frame memory M3. Conceptual diagram (d) Conceptual diagram of image data stored in the same frame memory M4

FIG. 12 is a block diagram of a video data storage device of a video decoding device of the video compression / decompression system according to Embodiment 4 of the present invention.

13A is a conceptual diagram of image data before the wavelet transform, and FIG. 13B is a conceptual diagram of image data after the wavelet transform.

14A is a conceptual diagram of image data stored in the frame memory M1, FIG. 14B is a conceptual diagram of image data stored in the frame memory M2, and FIG. 14C is a conceptual diagram of image data stored in the frame memory M3. Conceptual diagram (d) Conceptual diagram of image data stored in the same frame memory M4

FIG. 15 is a block diagram of a moving image compression / decompression system according to a fifth embodiment of the present invention.

FIG. 16 is a block diagram of a conventional video decoding device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image data compression means 2 Image data storage means 3 Image data decompression means 4 Control means 5, 6, 7, 8 Data bus 10 Subtractor 20 Orthogonal transformation circuit 30 Quantization circuit 31 Interpolation circuit 32 Inverse wavelet transformation circuit 33 Data interpolation circuit 40 variable length encoding circuit 41 memory control means 42 control circuit 50, 910 inverse quantization circuit 60, 920 inverse orthogonal transformation circuit 70, 930 adder 80 image data storage device 90, 950 motion compensation circuit 100 motion detection circuit 110, 900 Variable length decoding circuits 200, 210, 300, 310, 400, 410, 4
20, 430, 500, 600 Pixel blocks 510, 510a to 510d, 610, 620, 630
Block 940 Image data storage unit 1000 Video encoding device 1100 Multiplexing circuit 2000 Video decoding device 2100 Separation circuits A1 to AI, 941 Compression circuits M1 to MJ, 942 Frame memories B1 to BI, 943 Decompression circuits MC1 to MC4 Memory Control circuits M1a, M1b, M2a, M2b, M3a, M3b, M
4a to M4d Frame areas C1 to C3 Thinning circuits D1 and D2 Wavelet transform circuits E1 to E3 Data reduction circuit

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Mana Hamada             Matsushita Electric, 1006 Kadoma, Kazuma, Osaka             Sangyo Co., Ltd. F term (reference) 5C052 AA17 GA07 GB01 GC03 GC05                       GD09 GE04 GF02 GF03                 5C059 KK08 LB05 LB15 MA00 MA05                       MA24 MC11 MC38 ME01 PP01                       PP04 TA06 TA08 TA17 TA21                       TB03 TB04 TB07 TB08 TC41                       TD07 UA02 UA05 UA35 UA37                       UA38

Claims (20)

[Claims] A compression means for compressing image data; a first storage means for storing uncompressed image data of a plurality of frames in frame units; and a first storage means provided corresponding to the compression means. A second storage unit that stores the image data compressed by the compression unit in frame units; an image data expansion unit that is compressed by the compression unit and expands the image data stored in the second storage unit; An image data storage device comprising: A plurality of compression means for compressing image data; a first storage means for storing uncompressed image data of one or more frames in frame units; and a plurality of compression means corresponding to the plurality of compression means. A plurality of second storage units, each of which stores the image data compressed by the corresponding compression unit in a frame unit, each being compressed by the compression unit and stored in the second storage unit Image data decompressing means for decompressing image data, wherein each of the compression means has a different compression ratio. 3. The image data storage according to claim 2, wherein one or more of the predetermined compression means performs lossless compression, and the other compression means performs lossy compression. apparatus. 4. The image data decompression means includes a plurality of decompression means provided corresponding to the plurality of compression means, wherein the decompression means is compressed by a corresponding one of the compression means and a corresponding one of the second one. 4. The image data storage device according to claim 2, wherein the image data stored in the storage unit is expanded. 5. The compression means compresses image data by thinning out pixel data, and the image data expansion means expands the image data compressed by the compression means by interpolating pixel data. 4. The image data storage device according to claim 1, wherein: 6. The image processing apparatus according to claim 1, wherein the compression unit compresses the image data by reducing a predetermined block from a plurality of blocks composed of frequency domain components obtained by performing a wavelet transform on the image data. The image data decompression means, for the image data compressed by the compression means, by interpolating the predetermined block deleted by compression with predetermined data, by performing an inverse wavelet transform, 4. The image data storage device according to claim 1, wherein the image data compressed by the compression unit is expanded. 7. The first storage means and the second storage means store the first storage means, the second storage means, the compression means, and the image data decompression means. 5. The image data storage device according to claim 1, further comprising control means for giving an instruction to change a storage mode of the image data being processed. 8. The image data stored in the first storage means and the second storage means with respect to the first storage means, the second storage means, and the compression means. 7. The image data storage device according to claim 5, further comprising control means for giving an instruction to change a storage mode. 9. The compression means performs compression in units of m × n (m and n are natural numbers) pixels, and the image data decompression means performs m × n (m and n are natural numbers).
9. The image data storage device according to claim 1, wherein the image data is expanded in units of blocks of pixels. 10. A plurality of compression means for compressing image data; a first storage means for storing uncompressed image data of one or more frames in frame units; and a plurality of compression means corresponding to the plurality of compression means. A plurality of second storage units, each of which stores the image data compressed by the corresponding compression unit in a frame unit, each being compressed by the compression unit and stored in the second storage unit Image data decompressing means for decompressing image data, wherein each of the compression means has a different compression method. 11. An image data storage device according to claim 1, wherein image data of a frame stored in said image data storage device is used as image data of a reference frame, and encoding using inter-picture prediction is performed. An encoding device characterized by the following. 12. A predetermined number of past frames that are temporally continuous with respect to a current frame to be encoded, and said current frame to be encoded.
In the frame group consisting of, a plurality of groups each consisting of a predetermined number of frames are configured so as to be temporally continuous from the present to the past, and the past frames are used when performing inter-screen prediction. A group including reference frames, wherein the group including the current frame to be encoded includes at least one reference frame; and the compression unit of the image data storage device is provided corresponding to a group including only reference frames. And compressing the image data of the reference frame belonging to the corresponding group, wherein the first storage means of the image data storage device is provided corresponding to the group including the frame to be currently encoded. Storing uncompressed image data of a frame belonging to a group to be stored in the second group of the image data storage device. 12. The apparatus according to claim 11, wherein the means is provided corresponding to the group consisting of only the reference frames, and stores the image data of the reference frames belonging to the corresponding group, compressed by the corresponding compression means. Encoding device. 13. An image data storage device according to claim 2, wherein image data of a frame stored in the image data storage device is used as reference frame image data, and encoding using inter-picture prediction is performed. An encoding device characterized by the following. 14. A predetermined number of past frames that are temporally continuous with respect to a current encoding target frame, and said current encoding target frame;
In the frame group consisting of, a plurality of groups each consisting of a predetermined number of frames are configured so as to be temporally continuous from the present to the past, and the past frames are used when performing inter-screen prediction. A reference frame, wherein the group including the current encoding target frame includes only the current encoding target frame, or includes the current encoding target frame and a reference frame; The plurality of compression units of the image data storage device are provided corresponding to a plurality of groups consisting only of reference frames, and the compression unit compresses image data of reference frames belonging to the corresponding groups, The first storage means of the apparatus is provided corresponding to a group including the frame to be currently encoded, and Storing uncompressed image data of a frame belonging to a corresponding group, wherein the plurality of second storage units of the image data storage device are provided corresponding to a plurality of groups consisting only of reference frames; Each of the two storage means stores image data of a reference frame belonging to a corresponding group, which is compressed by the corresponding compression means, and a compression ratio of the compression means corresponds to a reference belonging to the group corresponding to the compression means. 14. The encoding apparatus according to claim 13, wherein a compression ratio of the compression unit corresponding to a group including a reference frame temporally closer to the current encoding target frame than a frame to be encoded is larger than a compression ratio of the compression unit. 15. An image data storage device according to claim 1, wherein decoding using inter-picture prediction is performed using image data of a frame stored in the image data storage device as image data of a reference frame. A decoding device characterized by the above-mentioned. 16. A predetermined number of past frames which are temporally continuous with respect to a current frame to be decoded, and said current frame to be decoded.
In the frame group consisting of, a plurality of groups each consisting of a predetermined number of frames are configured so as to be temporally continuous from the present to the past, and the past frames are used when performing inter-screen prediction. A group including reference frames, the group including the current frame to be decoded includes at least one reference frame; and the compression unit of the image data storage device is provided corresponding to a group including only reference frames. Compressing image data of a reference frame belonging to a corresponding group, wherein the first storage means of the image data storage device is provided corresponding to a group including the frame to be currently decoded, Storing uncompressed image data of a frame belonging to a group to be stored in the second group of the image data storage device. 16. The device according to claim 15, wherein the means is provided corresponding to the group consisting of only the reference frame, and stores the image data of the reference frame belonging to the corresponding group, which is compressed by the corresponding compression means. Decryption device. 17. An image data storage device according to claim 2, wherein decoding using inter-picture prediction is performed using image data of a frame stored in the image data storage device as image data of a reference frame. A decoding device characterized by the above-mentioned. 18. A predetermined number of past frames that are temporally continuous with respect to a current frame to be decoded, and said current frame to be decoded;
In the frame group consisting of, a plurality of groups each consisting of a predetermined number of frames are configured so as to be temporally continuous from the present to the past, and the past frames are used when performing inter-screen prediction. A group including a frame to be decoded and a frame to be currently decoded; or a group including only the frame to be currently decoded or a frame to be decoded and a reference frame, The plurality of compression units of the image data storage device are provided corresponding to a plurality of groups consisting only of reference frames, and the compression unit compresses image data of reference frames belonging to the corresponding groups, The first storage means of the apparatus is provided corresponding to a group including the current frame to be decoded, and Storing uncompressed image data of a frame belonging to a corresponding group, wherein the plurality of second storage units of the image data storage device are provided corresponding to a plurality of groups consisting only of reference frames; Each of the two storage means stores image data of a reference frame belonging to a corresponding group, which is compressed by the corresponding compression means, and a compression ratio of the compression means corresponds to a reference belonging to the group corresponding to the compression means. 18. The decoding apparatus according to claim 17, wherein a compression ratio of the compression unit corresponding to a group including a reference frame temporally closer to the current frame to be decoded than the frame to be decoded is larger than a frame. 19. An encoding device according to claim 11, further comprising: a decoding device according to claim 15, wherein said encoding device has information on compression of image data by said image data storage device; And multiplexing means for multiplexing the image data subjected to the above, and generating multiplexed data, wherein the decoding device receives the multiplexed data, the information regarding the compression, and the encoded data. A compression / decompression system, further comprising a separation unit for separating image data and image data. 20. An encoding device according to claim 13, further comprising: a decoding device according to claim 17, wherein said encoding device has information on compression of image data by said image data storage device; And multiplexing means for multiplexing the image data subjected to the above, and generating multiplexed data, wherein the decoding device receives the multiplexed data, the information regarding the compression, and the encoded data. A compression / decompression system, further comprising a separation unit for separating image data and image data.