WO2015139180A1 - Image coding method and device and image processing device - Google Patents

Abstract

Provided are an image coding method and device and an image processing device. The image coding method comprises: with respect to a pixel of a to-be-coded image area, comparing the pixel value of the pixel with the pixel value of either a pixel at a same position in the preceding row or a pixel at a same position in the preceding column; determining, on the basis of the comparison result, whether or not a copy mode is used for the pixel; and, insofar as use of the copy mode is determined, bit-stream coding the pixel by using the copy mode. The image coding method not only allows for coding of pixels by using the copy mode as much as possible, thus increasing coding efficiency without incurring additional conversion costs, but also is applicable in a case that a palette mode is not fully used.

Description

 Image coding method, device and image processing device

 The present invention relates to the field of graphic image technology, and in particular, to an image encoding method and apparatus, and an image processing apparatus.

Background technique

 Palette-based coding is widely used in graphic image technology (especially video coding technology). In the encoding process, for the image area to be encoded, for example, a coding unit (CU), including a plurality of pixels having color values (for example, RGB mode, having 24 bits of true color); The storage capacity of the image, usually pointing the pixel to the data index of the palette. During the decoding process, the color value of each output pixel can be determined by looking up the palette with the corresponding data index.

The palette is a set of pixel values. For pixels whose pixel values are in the palette, only the corresponding pixel index (pixel inde _X ) of the pixel value in the palette is used. Thereby, only the palette and the index corresponding to the pixels in the coding unit can be bit-stream encoded, and the bit cost of the encoding can be reduced.

 The following is a list of documents useful for understanding the present invention and conventional techniques, which are incorporated herein by reference as if fully set forth herein.

 [Non-Patent Document 1]: JCTVC-O0182. Xun Guo, etc, Microsoft, Major-color-based screen content coding.

 [Non-Patent Document 2]: JCTVC-N0249. Liwei Guo, etc, Qualcomm, Modified Palette Mode for Screen Content Coding.

 It should be noted that the above description of the technical background is only for the purpose of facilitating the clear and complete description of the technical solutions of the present invention, and is convenient for understanding by those skilled in the art. The above technical solutions are not considered to be well known to those skilled in the art simply because these solutions are set forth in the background section of the present invention.

Summary of the invention

Currently, in order to further reduce the bit cost, if the index value of a pixel in the palette is the same as the previous row If the set pixel has the same index value in the palette, the pixel can be bitstream encoded in a copy mode. But the inventor found that: The current solution needs to convert the pixels into indexes in the palette for comparison, which requires additional conversion cost; and in the case where the palette mode is not fully adopted (for example, the combination of Palette mode and escape mode) Next, pixels that do not use the palette mode cannot use copy mode, thereby reducing coding efficiency.

 Embodiments of the present invention provide an image encoding method, apparatus, and image processing apparatus, the purpose of which is to enable a pixel to be encoded in a copy mode as much as possible, thereby improving encoding efficiency without adding additional conversion cost.

 According to a first aspect of the embodiments of the present invention, an image encoding method is provided, the image encoding method comprising:

 For a pixel of the image area to be encoded, comparing the pixel value of the pixel with the pixel value of the same position of the previous row or the pixel value of the same position of the previous column;

 Determining whether the pixel adopts a copy mode according to a comparison result;

 In the case where it is determined that the copy mode is employed, the pixel is subjected to bit stream encoding using the copy mode. According to a second aspect of the embodiments of the present invention, there is provided an image encoding apparatus, the image encoding apparatus comprising:

 Comparing unit, for a pixel of the image area to be encoded, comparing the pixel value of the pixel with the pixel value of the same position of the previous row or the pixel value of the same position of the previous column;

 a determining unit, determining, according to the comparison result, whether the pixel adopts a copy mode;

 The stream coding unit, in the case of determining that the copy mode is employed, performs bit stream coding on the pixels in a copy mode.

 According to a third aspect of the embodiments of the present invention, there is provided an image processing apparatus, the image processing apparatus comprising:

 An image encoding device as described above;

 A decoding device that decodes the bitstream to obtain an image.

 According to still another aspect of an embodiment of the present invention, a computer readable program is provided, wherein when the program is executed in an image processing apparatus, the program causes a computer to perform image encoding as described above in the image processing apparatus method.

According to still another aspect of an embodiment of the present invention, a storage medium storing a computer readable program, wherein the computer readable program causes a computer to execute an image encoding side as described above in an image processing apparatus Law.

 An advantageous effect of the embodiment of the present invention is to determine whether a pixel adopts a copy mode by using pixel values for comparison, and not only can the pixel be encoded in a copy mode as much as possible, thereby improving coding efficiency without adding additional conversion cost, and can be applied to no The case of full palette mode.

 Specific embodiments of the present invention are disclosed in detail with reference to the following description and drawings, which illustrate the manner in which the principles of the invention may be employed. It should be understood that the embodiments of the invention are not limited in scope. The embodiments of the present invention include many variations, modifications, and equivalents within the spirit and scope of the appended claims.

 Features described and/or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, in combination with, or in place of, features in other embodiments. .

 It should be emphasized that the term "comprising" or "comprising" is used to mean the presence of a feature, component, step or component, but does not exclude the presence or addition of one or more other features, components, steps or components. DRAWINGS

 Many aspects of the invention can be better understood with reference to the following drawings. The components in the figures are not drawn to scale, but only to illustrate the principles of the invention. In order to facilitate the illustration and description of some parts of the invention, the corresponding parts in the drawings may be enlarged or reduced.

 The elements and features described in one of the figures or one embodiment of the invention may be combined with elements and features illustrated in one or more other figures or embodiments. In the accompanying drawings, like reference numerals refer to the

 1 is a schematic diagram of an example of a coding unit according to an embodiment of the present invention;

 2 is a schematic diagram of another example of a coding unit according to an embodiment of the present invention;

 3 is a schematic diagram of another example of a coding unit according to an embodiment of the present invention;

 4 is a schematic flow chart of an image encoding method according to an embodiment of the present invention;

 FIG. 5 is a schematic structural diagram of an image encoding apparatus according to an embodiment of the present invention; FIG.

 Figure 6 is a block diagram showing the structure of an image processing apparatus according to an embodiment of the present invention.

detailed description

The foregoing and other features of the invention will be apparent from the In the description The specific embodiments of the present invention are specifically disclosed in the drawings and the drawings, which illustrate some embodiments in which the principles of the invention may be employed. It is understood that the invention is not limited to the described embodiments. All modifications, variations and equivalents are intended to be included within the scope of the appended claims.

 1 is a schematic diagram showing an example of a coding unit according to an embodiment of the present invention, showing a case of a coding unit. As shown in Fig. 1, the coding unit has 8 X 8 pixels; wherein pixels having the same pixel value use the same symbol to represent pixel values, such as C0, Cl, ..., C7. If the current palette-based encoding method is used, it will be encoded with a palette size (represented by maxjDalette-size) that is larger than the number of pixels, ie max_palette_size>9, for example max_palette_size=32. This causes all pixels in the coding unit to be encoded in a palette mode. At this point the palette Palettel={ C0, Cl, C2, C3, C4, C5, C6, CI ) has 8 elements in the palette.

 FIG. 2 is a schematic diagram of another example of a coding unit according to an embodiment of the present invention, showing an index situation after the coding unit of FIG. 1 adopts Palettel. If the current copy mode method is used, the index values in Figure 2 are used for comparison to determine whether the pixel uses copy mode. That is, for one of the pixels, in the case of horizontal scanning, it is determined whether the pixel index of the pixel is the same as the pixel index of the same position in the previous row, and if the same, the pixel is determined to be copy mod

 For example, in FIG. 2, the pixel index of the second row is the same as the pixel index of the same position of the first row (both 00122103), and the pixel index of the first 7 pixel index of the third row and the same position of the second row The same (both 0012210), you can determine the 15 pixels in Figure 1, that is, from (0,1) (1,1) ······ to (7,1), and (0,2) ( 1,2) ··· ··· (6, 2) can use copy mode. Thus (0,1) pixels of copy run = 15.

 However, the scheme requires that the pixels be converted to an index in the palette for comparison, requiring additional conversion costs. In addition, this scheme reduces coding efficiency when palette mode is not fully used (for example, a combination of Palette mode and escape mode).

 The following uses the non-palette mode (also called escape mode) for C3 and C5 in Fig. 1, and the other pixels use the palette mode as an example. At this point the palette Palette2={ C0, Cl, C2, C4, C6, CI) has 6 elements in the palette.

FIG. 3 is a schematic diagram of another example of a coding unit according to an embodiment of the present invention, showing an index situation after the coding unit of FIG. 1 adopts Pal _e tte2. As shown in FIG. 3, the index of the pixel value C0 in the palette is 0, the index of the pixel value C1 in the palette is 1, the index of the pixel value C2 in the palette is 2, and the pixel value C4 is adjusted. The index in the swatch is 3, the index of the pixel value C6 in the palette is 4, and the index of the pixel value C7 in the palette is 5. Correct There is no corresponding index value for C3 and C5.

 At this time, if the current copy mode method is adopted, that is, if the index value in FIG. 3 is used for comparison to determine whether the pixel adopts the copy mode, then the 7 pixels in FIG. 1 can be determined, that is, from (0, 1) (1, 1). )...to (6,1) copy mode can be used, and copy mode cannot be used for pixels corresponding to C3. Thus (0,1) pixels of copyrun=7, not only require additional conversion costs, but also reduce coding efficiency.

 The present invention will be described in detail below with respect to the above technical problems. Example 1

 An embodiment of the present invention provides an image encoding method. FIG. 4 is a schematic flowchart of an image encoding method according to an embodiment of the present invention. As shown in FIG. 4, the image encoding method includes:

 Step 401: Compare, for a pixel of the image to be encoded area, a pixel value of the pixel with a pixel value of a pixel of the same row in the previous row or a pixel of a pixel of the same row of the previous column;

 Step 402: Determine, according to the comparison result, whether the pixel adopts a copy mode.

 Step 403: When it is determined that the copy mode is adopted, the pixel is subjected to bit stream coding by using a copy mode.

 In this embodiment, a plurality of pixels can be compared and judged one by one using pixel values. When it is determined that the copy mode is adopted, the pixel is subjected to bit stream encoding by using a copy mode; when it is determined that the copy mode is not adopted, the pixel is subjected to an existing method (for example, using a pixel index or using a pixel) Value) Perform bitstream encoding. Regarding the specific content of the bit stream coding, reference may be made to related art.

 In this embodiment, both horizontal scanning and vertical scanning are applicable.

 In one embodiment, when the horizontal scanning mode is employed, the pixel value of the pixel can be compared to the pixel value of the pixel at the same position in the previous row. For example, in the coding unit shown in FIG. 1, the pixels of the second row may be compared with the pixels of the same position in the first row, respectively, and the pixels of the third row may be respectively the pixels of the same position in the second row. Compare.

 That is, (0,1) pixels are compared with (0,0) pixels for pixel values, (1,1) pixels are compared with (1,0) pixels for pixel values, ..., (6,1) pixels and (6, 0) Pixels are compared for pixel values, (7, 1) pixels are compared with (7, 0) pixels for pixel values; (0, 2) pixels are compared with (0, 1) pixels for pixel values, ..., (6, 2) Pixels are compared with (6,1) pixels for pixel values.

In this embodiment, the pixel value of the pixel is the same as the pixel value of the pixel at the same position in the previous row. In this case, it can be determined that the pixel adopts a copy mode. Whereby lossless coding (lossless _C oding). For example, if the pixel value of the (0,1) pixel is the same as the pixel value of the (0,0) pixel, it can be determined that the (0,1) pixel adopts the copy mode; ...; (7,1) pixel pixel value and ( 7,0) The pixel value of the pixel is the same, then it can be determined that the (7,1) pixel adopts copymode; ...;; (6, 2) pixel pixel value is the same as (6, 1) pixel pixel value, then it can be determined ( 6,2) The pixel uses copymode.

 Thus, even in the case where the palette mode is not completely used, 15 pixels in the coding unit shown in FIG. 3, that is, from (0, 1) (1, 1) ... to (7, 1), and (0,2) (1,2) ...... (6,2) Copymode can still be used. Thus (0,1) pixels of copy run = 15, so that not only does not require additional conversion costs, but does not reduce coding efficiency.

 In this embodiment, it is also possible to determine that the pixel adopts a copy mode if a difference between a pixel value of the pixel and a pixel value of a pixel at the same position of the previous row is less than a preset threshold. As a result, lossy coding can be realized. As for the specific value of the preset threshold, it can be determined according to the actual situation, for example, it can be determined according to the empirical value or actual needs.

 In another embodiment, when the vertical scanning mode is employed, the pixel value of the pixel can be compared with the pixel value of the pixel at the same position in the previous column. For example, in the coding unit shown in FIG. 1, the pixels of the second column may be compared with the pixels of the same position in the first column, respectively, and the pixels of the third column may be respectively the pixels of the same position in the second column. Compare. The specific manner is similar to the horizontal scanning, and will not be described here.

In this embodiment, in a case where the pixel value of the pixel is the same as the pixel value of the pixel at the same position in the previous column, it may be determined that the pixel adopts the copy mode. Therefore, lossless coding can be realized. Further, in a case where the difference between the pixel value of the pixel and the pixel value of the pixel at the same position in the previous column is smaller than a preset threshold, it is determined that the pixel adopts the copy mode. This makes it possible to implement lossy coding (lo _SS y _CO ding).

 It can be seen from the above embodiment that by using pixel values for comparison to determine whether the pixel adopts the copy mode, not only can the pixel be encoded in the copy mode as much as possible, the coding efficiency is improved without adding additional conversion cost, and the method can be applied to the incomplete use of the modulation. Swatch mode situation. Example 2

 An embodiment of the present invention provides an image encoding apparatus, which corresponds to the image encoding method in Embodiment 1, and the same content is not described again.

Fig. 5 is a block diagram showing the structure of an image coding apparatus according to an embodiment of the present invention. It is worth noting that Figure 5 only The components related to the present invention are schematically shown, and are not shown for other components of the image encoding apparatus, and reference may be made to the prior art.

 As shown in FIG. 5, the image encoding apparatus 500 includes: a comparing unit 501, a determining unit 502, and a stream encoding unit 503; wherein, the comparing unit 501 compares the pixel value of the pixel with the previous row for one pixel of the image area to be encoded. Comparing the pixel values of the pixels at the same position or the pixels at the same position in the previous column; the determining unit 502 determines whether the pixel adopts the copy mode according to the comparison result; and when the stream encoding unit 503 determines that the copy mode is adopted, The pixels are bitstream encoded using a copy mode.

 In one embodiment, the comparing unit 501 may be specifically configured to: when the horizontal scanning mode is adopted, compare the pixel value of the pixel with the pixel value of the pixel at the same position in the previous row. The determining unit 502 may be specifically configured to: when the pixel value of the pixel is the same as the pixel value of the pixel at the same position of the previous row, determining that the pixel adopts a copy mode; or before the pixel value of the pixel In the case where the difference in pixel values of pixels of the same position in one row is less than a preset threshold, it is determined that the pixel adopts a copy mode.

 In another embodiment, the comparing unit 501 is specifically configured to: when the vertical scanning mode is adopted, compare the pixel value of the pixel with the pixel value of the pixel in the same position of the previous column. The determining unit 502 may be specifically configured to: when the pixel value of the pixel is the same as the pixel value of the pixel at the same position in the previous column, determining that the pixel adopts a copy mode; or before the pixel value of the pixel In the case where the difference in pixel values of a column of pixels of the same position is less than a preset threshold, it is determined that the pixel adopts a copy mode.

 It can be seen from the above embodiment that by using pixel values for comparison to determine whether the pixel adopts the copy mode, not only can the pixel be encoded in the copy mode as much as possible, the coding efficiency is improved without adding additional conversion cost, and the method can be applied to the incomplete use of the modulation. Swatch mode situation. Example 3

 An embodiment of the present invention provides an image processing apparatus, including: the image encoding apparatus according to Embodiment 2; and a decoding apparatus.

 Figure 6 is a block diagram showing the structure of an image processing apparatus according to an embodiment of the present invention. As shown in FIG. 6, the image processing apparatus 600 may include: a central processing unit (CPU) 200 and a memory 210; the memory 210 is coupled to the central processing unit 200. The memory 210 can store various data; in addition, a program for information processing is stored, and the program is executed under the control of the central processing unit 200.

In one embodiment, the functionality of image encoding device 500 may be integrated into central processor 200. Wherein, the central processing unit 200 can be configured to implement the image encoding method as described in Embodiment 1.

 In another embodiment, the image encoding device 500 may be configured separately from the central processing unit. For example, the image encoding device 500 may be configured as a chip connected to the central processing unit 200, and the image encoding device 500 may be implemented by control of the central processing unit. Features.

 In addition, as shown in FIG. 6, the image processing apparatus 600 may further include: an input and output unit 220, a display unit 230, and the like; wherein the functions of the components are similar to those of the prior art, and details are not described herein again. It is to be noted that the image processing apparatus 600 does not necessarily have to include all the components shown in FIG. 6; further, the image processing apparatus

600 may also include components not shown in Figure 6, reference may be made to the prior art.

 The embodiment of the present invention also provides a computer readable program, wherein when the program is executed in an image processing apparatus, the program causes a computer to execute the image encoding method described in Embodiment 1 in the image processing apparatus.

 The embodiment of the present invention further provides a storage medium storing a computer readable program, wherein the computer readable program causes the computer to execute the image encoding method described in Embodiment 1 in an image processing apparatus.

 The above apparatus and method of the present invention may be implemented by hardware, or may be implemented by hardware in combination with software. The present invention relates to a computer readable program that, when executed by a logic component, enables the logic component to implement the apparatus or components described above, or to cause the logic component to implement the various methods described above Or steps. The present invention also relates to a storage medium for storing the above program, such as a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory, or the like.

 One or more of the functional blocks described in the figures and/or one or more combinations of functional blocks may be implemented as a general purpose processor, digital signal processor (DSP) for performing the functions described herein. An application specific integrated circuit (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or any suitable combination thereof. One or more of the functional blocks described with respect to the figures and/or one or more combinations of functional blocks may also be implemented as a combination of computing devices, eg, a combination of a DSP and a microprocessor, multiple microprocessors One or more microprocessors in conjunction with DSP communication or any other such configuration.

 The present invention has been described in connection with the specific embodiments thereof, and it should be understood by those skilled in the art that these descriptions are not intended to limit the scope of the invention. A person skilled in the art can make various modifications and changes to the invention in accordance with the spirit and the principles of the invention, which are also within the scope of the invention.

Claims

claims 1. An image coding method, characterized in that the image coding method includes: For a pixel in the image area to be encoded, compare the pixel value of the pixel with the pixel value of the pixel at the same position in the previous row or the pixel at the same position in the previous column; Determine whether the pixel adopts copy mode according to the comparison result; If it is determined that the copy mode is used, the copy mode is used for bitstream encoding of the pixel. 2. The image encoding method according to claim 1, wherein comparing the pixel value of the pixel with the pixel value of the pixel at the same position in the previous row or the pixel at the same position in the previous column includes: When using the horizontal scanning mode, the pixel value of the pixel is compared with the pixel value of the pixel at the same position in the previous row. 3. The image encoding method according to claim 2, wherein determining whether the pixel adopts copy mode according to the comparison result includes: In the case where the pixel value of the pixel is the same as the pixel value of the pixel at the same position in the previous row, it is determined that the pixel adopts the copy mode; or When the difference between the pixel value of the pixel and the pixel value of the pixel at the same position in the previous row is less than the preset threshold, it is determined that the pixel adopts the copy mode. 4. The image encoding method according to claim 1, wherein comparing the pixel value of the pixel with the pixel value of the pixel at the same position in the previous row or the pixel at the same position in the previous column includes: When vertical scanning is used, the pixel value of the pixel is compared with the pixel value of the pixel at the same position in the previous column. 5. The image encoding method according to claim 4, wherein determining whether the pixel adopts copy mode according to the comparison result includes: In the case where the pixel value of the pixel is the same as the pixel value of the pixel at the same position in the previous column, it is determined that the pixel adopts the copy mode; or When the difference between the pixel value of the pixel and the pixel value of the pixel at the same position in the previous column is less than the preset threshold, it is determined that the pixel adopts the copy mode. 6. An image coding device, characterized in that, the image coding device includes: The comparison unit: for a pixel in the image area to be encoded, the pixel value of the pixel is the same as that of the previous row. Compare the pixel values of the pixel at the position or the pixel at the same position in the previous column; A judging unit, judging whether the pixel adopts the copy mode according to the comparison result; The stream encoding unit, when it is determined that the copy mode is used, uses the copy mode to perform bit stream encoding on the pixel. 7. The image encoding device according to claim 6, wherein the comparison unit is specifically configured to: when the horizontal scanning mode is adopted, compare the pixel value of the pixel with the pixel value of the pixel at the same position in the previous row. 8. The image encoding device according to claim 7, wherein the determination unit is specifically configured to: when the pixel value of the pixel is the same as the pixel value of the pixel at the same position in the previous row, determine that the pixel adopts copy mode; or When the difference between the pixel value of the pixel and the pixel value of the pixel at the same position in the previous row is less than the preset threshold, it is determined that the pixel adopts the copy mode. 9. The image encoding device according to claim 6, wherein the comparison unit is specifically configured to: when the vertical scanning mode is adopted, compare the pixel value of the pixel with the pixel value of the pixel at the same position in the previous column. 10. The image encoding device according to claim 9, wherein the determination unit is specifically configured to: when the pixel value of the pixel is the same as the pixel value of the pixel at the same position in the previous column, determine that the pixel adopts copy mode; or When the difference between the pixel value of the pixel and the pixel value of the pixel at the same position in the previous column is less than the preset threshold, it is determined that the pixel adopts the copy mode. 11. An image processing device, the image processing device includes: The image coding device according to any one of claims 6 to 10; and A decoding device decodes the bit stream to obtain images.