JP2002112192A - Image recording and playback device - Google Patents

Abstract

(57) [Summary] [Problem] To record an intermittent image with high compression and reproduce it. SOLUTION: At the time of recording, images captured by a plurality of cameras are accumulated as intermittent images in recording temporary storage memories 3 and 4, and the intermittent images are collectively read for each image of the same camera and sequentially read out. The image data is converted into a full frame image by inter-compression and recorded on the recording medium 6. At the time of reproduction, images recorded on the recording medium 6 are collectively read for each image of the same camera, sequentially read out, decompressed by the expansion means 7 and stored in the reproduction temporary storage memory 8, and read out from the reproduction temporary storage memory 8. The expanded image is expanded in the display memory 9 and the monitor 11
To display.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital image recording / reproducing apparatus applied to a monitoring system or the like.

[0002]

2. Description of the Related Art A security monitoring system installed in a convenience store, an unmanned store, a bank, or the like is, for example, one video tape (VHS) using a frame switcher or the like for images captured by a plurality of monitoring cameras. The videotape is stored for a fixed period of time (for example, about two weeks) and can be used as evidence in the event of a crime.

[0003]

However, the method of recording on a video tape has a problem that the number of video tapes is enormous and bulky.

Therefore, a method of recording an image by compressing the image is considered as a method of recording the image by a digital method. As the image compression method, there are an intra-frame compression method such as JPEG and an inter-frame compression method such as MPEG.

[0005] The former intra-frame compression method compresses each frame individually, so that it does not depend on the correlation between frames.
Intermittent images recorded one frame at a time can be easily compressed, and are suitable for monitoring images and the like, in which images from a plurality of cameras are switched and recorded at high speed. There is a problem that a huge storage capacity is required.

On the other hand, the inter-frame compression method is a method of recording only a portion that changes between frames, and has the advantage of increasing the compression ratio.
(0 frames / sec) is the basis of compression, and since dropped frames are not allowed, intermittent images cannot be compressed, making it difficult to apply to a monitoring system that switches and records images from a plurality of cameras at high speed.

An object of the present invention is to provide an image recording / reproducing apparatus capable of recording an intermittent image with high compression in a monitoring system or the like, and capable of recording for a long time with a small storage capacity.

[0008]

According to a first aspect of the present invention, there is provided a selector for sequentially and repeatedly switching images picked up by a plurality of cameras in frame units, and a recording temporary memory for storing images obtained by the selector. A storage memory, compression means for sequentially reading out images stored in the recording temporary storage memory for each image of the same camera, converting the images into full-frame images by inter-frame compression, and recording the images compressed by the compression means. A recording medium to be read, a decompressing unit for sequentially reading and decompressing images recorded on the recording medium for each image of the same camera, a reproduction temporary storage memory for storing the image decompressed by the decompressing unit, A display memory for expanding the image read from the temporary storage memory for reproduction.

In a second aspect based on the first aspect, the writing area of the temporary storage memory for recording is designated in conjunction with the switching operation of the selector.

In a third aspect based on the first or second aspect, the temporary storage memory for recording is a two- or two-part temporary storage in which one is in a write state and the other is in a read state. Each of the temporary storage memories has a recording capacity that is equal to or longer than the time required for reading out an image therefrom and compressing the image by the compression means.

According to a fourth aspect of the present invention, in any one of the first to third aspects, reading from the reproduction temporary storage memory is sequentially switched to a captured image of a different camera or a specific one of the cameras. The processing is performed only on the captured image, and the read image is expanded in the display memory in a multi-part format.

In a fifth aspect based on the fourth aspect, the resolution of the frame image stored in the temporary storage memory for reproduction is reduced by the number of divisions of the display memory.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, an alarm input section is provided, the temporary storage memory for recording is a ring memory to which endless writing is performed, and the alarm input section is provided. The ring memory switches from a write operation to a read operation in response to an alarm input to the ring memory.

In a seventh aspect based on any one of the first to fifth aspects, an image read out from the temporary storage memory for reproduction and an image output from the selector are input to the input side of the display memory. Selection means for selecting one is provided.

In an eighth aspect based on any one of the first to fifth aspects, repetition of writing and reading to the recording temporary storage memory, repetition of writing and reading to the recording medium, and reproduction The repetition of writing and reading to the temporary storage memory is continued, and an image captured by the camera is developed in the display memory after a predetermined time has elapsed.

According to a ninth invention, in any one of the first to fifth inventions, reading means for reading a camera identification symbol contained in an image is provided on the output side of the selector, and the reproduction temporary An additional unit is provided for adding the camera identification symbol read by the reading unit to the image read from the storage memory.

In a tenth aspect based on any one of the first to ninth aspects, the recording temporary storage memory, the reproduction temporary storage memory, and the recording medium are hard disks.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [One Embodiment] FIG. 1 is an explanatory diagram of one embodiment of a recording / reproducing apparatus according to the present invention. Most of the images recorded by the surveillance system are captured by a fixed camera. Therefore, even if the image is an intermittent image, the correlation between frames is high for each camera. Therefore, in the present invention, the images intermittently extracted are collectively and temporarily stored for each camera, and the intermittent images of the same camera are recorded as continuous full frame images by using the inter-frame compression method.

In FIG. 1, (a) shows a recording unit, and (b) shows a reproducing unit. Here, recording when four cameras (not shown) are used will be described. Reference numeral 1 denotes a high-speed selector such as a frame switcher, which sequentially switches four continuous images picked up by four cameras in frame units so that an image of each camera becomes an intermittent image (one frame per four frames). Image). That is, of the four cameras, the frame image of the first camera, the frame image of the second camera,
Assuming that the frame image of the camera is the frame image of the fourth camera, the frames are captured in the temporal order of →→→→→→.

Reference numeral 2 denotes an A / D converter for converting the frame image into a digital image signal, and reference numerals 3 and 4 denote temporary storage memories such as FIFOs. On the other hand, the temporary storage memory 3 stores the above-described frame images in the fetching order, that is, in a temporal order of →→→→→→. The designation (address designation) of the writing area in the temporary storage memory 3 is sequentially performed in conjunction with the switching control of the selector 1. The frame image previously written in the other temporary storage memory 4 in the same manner is read out for each camera. That is, →→→ ・ ・ ・ →
→→→→ ・ ・ ・ →→→→→ ・ ・ ・ →→
The data is read in the order of →→→.

Then, the read intermittent image of the same camera is subjected to an inter-frame compression method (MP
EG etc.), and is compressed and converted into a full frame image of 30 frames / sec or a full frame image of a number close to 30 frames / sec.
It is recorded on a recording medium 6 such as a DD (hard disk).

At this time, the full frame image of the first camera is in the first recording area 601 of the recording medium 6, the full frame image of the second camera is in the second recording area 602, and the full frame image of the third camera is in the third recording area. The full frame image of the fourth camera is recorded in the recording area 603, and the full frame image of the fourth camera is recorded in the fourth recording area 604, respectively.

When the reading of the temporary storage memory 4 is completed, writing to the temporary storage memory 4 is performed, and the image written in the temporary storage memory 3 is read for each camera. The compression is performed between the frames, and then the data is recorded on the recording medium 6. Or later,
Write to the two temporary storage memories 3 and 4 alternately,
Reading is performed alternately, and the intermittent images captured by the four cameras are converted into full frame images for each camera, and
To record.

At the time of recording on the recording medium 6, time data is inserted into each image. Even if the time data of the imaging is inserted in the vertical blanking period of the image signal captured by the camera, the time data is lost during the compression process, so the time data is temporarily saved before the compression, The time data is inserted into the compressed image signal. In the original frame, the save time data is used as it is, and in the interpolation frame, the time data is calculated from the time data of the previous and next frames, and the time data is inserted.

The two temporary storage memories 3 and 4 are
One memory may be used in two sections. However, there is a margin for a recording capacity equal to or longer than the processing time for reading from the memory and compressing and recording on the recording medium 6, thereby enabling continuous image recording.

As described above, in the image recording, the intermittent images fetched by the selector 1 are alternately written into the two temporary storage memories 3 and 4 so as to be grouped for each camera, and are read alternately collectively for each camera. It is output and recorded on the recording medium 6 as a full frame image (30 frames / sec) by inter-frame compression. At this time, since the inter-frame compression processing is performed on the full frame image of each camera recorded on the recording medium 6, the data amount is extremely small, and the number of frames recorded on the recording medium 6 is dramatically increased. And recording for a long time becomes possible. Also,
Since the compression processing unit 5 used here is commonly used for frame images captured by each camera, the circuit scale does not become particularly large.

Reference numeral 7 denotes a decompression processing unit such as MPEG, which decompresses and reproduces a full frame image for each camera read from the recording medium 6. Reference numeral 8 denotes a temporary storage memory for reproduction, such as a FIFO, for storing the expanded and reproduced full-frame images, which can be simultaneously written and read, and accumulates a fixed amount of full-frame images collectively for each camera. Reference numeral 9 denotes a display memory on which the data written is displayed on a monitor. Reference numeral 10 denotes a D / A converter for converting the image data read from the display memory 9 into an analog signal.
Is a monitor.

When performing single-screen display, only the full-frame image of a specific camera is read out of the full-frame images of the four cameras from the recording medium 6 and the decompression processing unit 7
And writes it in the temporary storage memory 8 for reproduction, and expands this in the display memory 9. Then, the contents of the display memory 9 are sequentially updated at the full-frame or intermittently recorded time intervals. Therefore, the contents are displayed on the monitor 11. At this time, when the amount of the image stored in the temporary storage memory 8 becomes equal to or less than a certain amount, the readout from the recording medium 6 and the expansion processing by the expansion processing unit 7 are performed again, and the writing to the temporary storage memory 8 is performed. Do. As described above, by repeating the accumulation and the reading in the temporary storage memory 8, the reproduction can be performed on a single screen.

When the display is divided into four parts, the full frame images of the four cameras are read out from the image recording medium 6 collectively for each camera, decompressed by the decompression processing unit 7 and written into the temporary storage memory 8. Then, of the full-frame images of the four cameras stored in the temporary storage memory 8,
By reading the frame images of the cameras at the same time and developing them in the display memory 9 in the form of four divisions, the images of the four cameras are reproduced on the monitor 11 in four parts.

At the time of reproduction by the monitor 11, fast forward can be performed. In the case of single screen reproduction, fast forward reproduction by skipping frames is performed. If the number of skipped frames is small, fast forward is at low speed, and if it is large, fast forward is at high speed. In the frame skipping, any one of the recording areas 601 to 604 of the recording medium 6 is read every predetermined number of frames. At this time, the image read from the recording medium 6 and processed by the decompression processing unit 7 is directly converted into an analog signal by the D / A converter 10 and displayed on the monitor 11. That is, the temporary storage memory 8 and the display memory 9 are not used. On the other hand, in the case of a multi-split screen,
The image of each camera is stored in each of the recording areas 601 to 60 of the recording medium 6.
4, the data is skipped every predetermined frame and read out, fast-forwarded, reproduced, stored in the temporary storage memory 8, and displayed as described in the multi-segment display. Note that fast-forwarding can be performed in a full frame. In this case, reading out of the recording medium 6 and writing / reading out of the temporary storage memory 8 are accelerated as long as the processing time in the decompression processing unit 7 is secured.

[Specific Configuration Example] FIG. 2 is a diagram showing a specific configuration of the image recording / reproducing apparatus shown in FIG. 1, wherein (a) shows a recording unit and (b) shows a reproducing unit. The same components as those shown in FIG. 1 are denoted by the same reference numerals. Reference numerals 12 and 13 denote memory controllers for the temporary storage memories 3 and 4, one memory controller 12 controls writing to the temporary storage memory 3 or 4, and the other memory controller 13 reads data from the temporary storage memory 3 or 4. Control. Reference numeral 14 denotes a writing controller of the image recording / reproducing device 6, and reference numeral 15 denotes a CPU that controls a recording unit. Reference numeral 16 denotes a read controller of the image recording / reproducing device 6, 17 denotes a memory controller of the temporary storage memory 8 and the display memory 9, and 18 denotes a CPU that controls a reproducing unit. When the recording unit and the reproducing unit are integrated, the recording medium controllers 14 and 16 can be shared, and the CPUs 15 and 18 can be shared.

[Various Modifications of Embodiment] The above description has been made on the assumption that the camera is a fixed camera having a fixed field of view. However, a turning camera can also be used. In this revolving camera, the image being revolved has a reduced correlation between the frames, resulting in poor compression efficiency. Therefore, a turning determination input unit (not shown) for determining whether or not the camera is turning is provided, and when the images of the turning camera are stored in the temporary storage memories 3 and 4, the turning determination input unit is provided. A flag indicating the presence or absence of turning is added in accordance with the input determination signal, and this flag is referred to during compression by the compression processing unit 5,
During turning, the camera image is not recorded. Alternatively, it is desirable to switch to the intra-frame compression method during turning, and to perform processing such as thinning out the recording interval, that is, reducing the number of frames to be captured.

In the above description, the images are alternately written and read alternately in the temporary storage memories 3 and 4, but one or both of the temporary storage memories 3 and 4 are used as a single ring memory and cyclically stored therein. In other words, the memory is read out from the write operation at the timing when a signal indicating an alarm such as a burglary incident is input to a separately provided alarm input unit (not shown), that is, the intermittent image is updated endlessly and repeatedly written. The operation may be switched to start the compression and the writing to the recording medium 6. At this time, the image from a predetermined time before the occurrence of the alarm is stored in the recording medium 6, and a “pre-alarm” operation effective for monitoring use can be performed.

Also, when writing to the temporary storage memories 3 and 4 at the time of recording, the same image data is also expanded to the display memory 9 so that a real-time image (however, (Intermittent image) can be displayed on the monitor 11 as a single screen or a 4-split screen. To cope with this, a selection means (not shown) for selecting one of the output of the temporary storage memory 8 for reproduction and the output of the A / D converter 2 as a writing source to the display memory 9 is provided. Good.

After the writing to one of the temporary storage memories 3 and 4 is completed, the data is read out, compressed and read out while being recorded on the recording medium 6, and the monitor 11 is displayed in a single screen or a 4-split screen by the above-described method. In the case of displaying the image, the image is developed in the display memory 9 in order from the temporally oldest image, so that an image that is delayed for a certain time from the time when the image is actually captured is displayed on the monitor 11, and an alarm or the like is generated by the monitor. Even if the monitor 11 is observed after the detection, the situation before and after the occurrence of the abnormality can be accurately grasped.

Further, it is also possible to intentionally set the image developed from the temporary storage memory 8 for reproduction to the display memory 9 as an image of only one camera and display the image as a multi-divided screen in time series. For example, in the case of a 4-split screen,
Time series is displayed in order of upper left → upper right → lower left → lower right → upper left → ... etc. In such a case, changes in the time axis direction are simultaneously displayed on the multi-segment screen, so that an abnormal situation can be easily grasped.

When locating the image at the time of occurrence of the alarm, an image at a predetermined time to a predetermined time after the time of occurrence of the alarm is selected, expanded from the recording medium 6 to the temporary storage memory 8, and stored therefrom. Screens are picked up in chronological order, developed on the display memory 9 for multi-segmented screens, and displayed on a monitor, so that it is possible to grasp the situation before and after without performing operations such as playback from the head and reverse playback. Becomes At this time, the multi-divided image displayed on the monitor 11 is a still image before and after the alarm occurrence.

In this multi-split screen display, the pick-up image in the temporary storage memory 8 is changed variously for the images before and after the alarm is generated, and the display memory 9 is updated by the operation of the user who has confirmed the display. The most important points before and after the occurrence of the alarm can be easily searched and displayed.

When a full frame image is stored in the temporary storage memory 8 at the time of reproduction, the frame resolution is reduced to about a multi-segment screen, thereby reducing the memory area of the temporary storage memory 8 occupied by one frame image. can do. In this case, in the single-screen display, the temporary storage memory 8 is not used, and the frame image output from the decompression processing unit 7 and having the reduced resolution may be directly developed in the display memory 9. Thus, the capacity of the temporary storage memory 8 for reproduction can be significantly reduced without affecting the image resolution at the time of display. For example, in a 4-split screen display, the memory capacity can be reduced to 1/4.

In order to ensure the connectivity with the frame switcher on the reproduction side used in the current monitoring system, it is desirable to employ the following method. That is, a camera identification symbol superimposed on the vertical blanking period of the image signal obtained by the high-speed selector 1 is read, and each area of the temporary storage memories 3 and 4 (an area corresponding to the camera identification symbol) according to the read symbol. The image data is decompressed and stored, compressed, divided into areas for each camera, and recorded on the image recording medium 6. At the time of reproduction, the D / A converter 10
A camera identification symbol insertion unit (not shown) is provided on the output side of the camera, and the read camera identification symbol is superimposed on the blanking period of each of the four images. If a frame switcher (not shown) is inserted after the camera identification symbol insertion unit, four camera images handled by the image recording / reproducing apparatus of the present embodiment and another camera connected to the frame switcher can be used. It is possible to switch the image picked up by and display it on the monitor 11. The frame switcher can also supply power to the other camera.

In the above description, the temporary storage memories 3 and 4 for recording and the temporary storage memory 8 for reproduction can be shared with the recording medium 6 such as a hard disk. Thereby, the temporary storage memory 3, such as FIFO,
The need for 4, 8 is eliminated, and the cost can be reduced.

[0042]

As described above, according to the present invention, the obtained intermittent image is recorded on the recording medium as a full frame image by inter-frame compression, so that high compression can be realized and the required recording capacity per frame is reduced. This greatly reduces the recording time and enables long-time recording with a small recording capacity.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of an image recording / reproducing apparatus according to the present invention, wherein (a) is a recording unit and (b) is a reproducing unit.

FIGS. 2A and 2B are diagrams showing a specific configuration of an image recording / reproducing apparatus according to the present invention, wherein FIG. 2A shows a recording unit and FIG. 2B shows a reproducing unit.

Continued on the front page F-term (reference) 5C053 FA01 FA11 FA14 FA23 GA10 GA11 GB21 GB37 HA33 JA21 KA04 KA08 KA25 KA26 LA01 LA06 5C054 AA01 AA05 CA04 CC03 CH01 EA01 EA07 FD00 FE02 GA00 GB02 HA19 5C059 KK36 LA01 0005 KK36 LA01 MA05 UA33 5D044 AB07 BC01 CC05 DE49 EF03 EF05 FG10 FG18 GK08 5D080 BA03 DA07 EA01 EA03 GA01

Claims (10)

[Claims] 1. A selector for repeatedly switching images picked up by a plurality of cameras in a frame unit, a recording temporary storage memory for storing images obtained by the selector, and an image stored in the recording temporary storage memory. A compression unit for sequentially reading out the images of the camera collectively and converting them into a full frame image by inter-frame compression, a recording medium for recording the image compressed by the compression unit, and an image recorded on the recording medium by the same camera Expansion means for reading and expanding the images collectively for each image, a reproduction temporary storage memory for storing the image expanded by the expansion means, and a display memory for expanding the image read from the reproduction temporary storage memory. An image recording / reproducing apparatus, comprising: 2. The image recording / reproducing apparatus according to claim 1, wherein a write area of said temporary storage memory for recording is designated in conjunction with a switching operation of said selector. Playback device. 3. The image recording / reproducing apparatus according to claim 1, wherein the temporary storage memory for recording has two or two sections, one of which is controlled to be in a reading state when the other is in a writing state. An image recording / reproducing apparatus comprising a storage memory, wherein each of the temporary storage memories has a recording capacity equal to or longer than a time required for reading an image therefrom and compressing the image by the compression means. 4. The image recording / reproducing apparatus according to claim 1, wherein reading from the temporary storage for reproduction is sequentially switched to an image picked up by a different camera or a specific one of the cameras. An image recording / reproducing apparatus, wherein only the captured image is read and the read image is developed in the display memory in a multi-part format. 5. The image recording / reproducing apparatus according to claim 4, wherein the resolution of a frame image stored in said temporary storage for reproduction is reduced by the number of divisions of said display memory. Image recording and reproducing device. 6. The image recording / reproducing apparatus according to claim 1, further comprising: an alarm input unit, wherein the recording temporary storage memory is a ring memory to which writing is performed endlessly, and wherein the alarm input is performed. An image recording / reproducing apparatus wherein the ring memory switches from a write operation to a read operation in response to an alarm input to the unit. 7. The image recording / reproducing apparatus according to claim 1, wherein an image read from the temporary storage memory for reproduction and an image output from the selector are input to an input side of the display memory. An image recording / reproducing apparatus provided with a selection means for selecting one of the following. 8. The image recording / reproducing apparatus according to claim 1, wherein writing and reading to and from the recording temporary storage memory are repeated, and writing and reading to and from the recording medium are repeated. An image recording / reproducing apparatus, wherein writing and reading of data to and from a temporary storage memory for reproduction are repeated, and an image captured by the camera is developed in the display memory after a predetermined time has elapsed. 9. The image recording / reproducing apparatus according to claim 1, further comprising: reading means for reading a camera identification symbol included in an image on an output side of said selector, wherein said reproducing means comprises: An image recording / reproducing apparatus, further comprising an adding unit for adding a camera identification symbol read by the reading unit to an image read from a temporary storage memory. 10. The image recording / reproducing apparatus according to claim 1, wherein the recording temporary storage memory, the reproduction temporary storage memory, and the recording medium are hard disks. Image recording and playback device.