DECODING METHOD AND APPARATUS, ENCODING METHOD AND APPARATUS, AND CORRESPONDING CODER AND DECODER

RU2025104720APending Publication Date: 2026-08-28HUAWEI TECH CO LTD
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Patent Information

Application Number
RU2025104720
Authority / Receiving Office
RU · RU
Patent Type
Applications
Current Assignee / Owner
Filing Date
2025-02-28
Publication Date
2026-08-28

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Claims

1. A decoding method comprising the steps of: a bit stream of an image to be decoded is obtained, wherein the image to be decoded comprises a block to be decoded in a high-frequency sub-range obtained by means of a wavelet transform; obtain a code table corresponding to the block, to be decoded, wherein the code table is a code table selected from N code tables, wherein the N code tables correspond to different probability distributions of the amplitudes of the coefficients of the high-frequency subrange, where N is a positive integer and N≥2; and decoding the bit stream based on the code table to obtain a reconstructed value for the coefficient value of the block to be decoded.

2. The method according to claim 1, wherein the block to be decoded is a block of coefficients in the high-frequency sub-band obtained by performing a wavelet transform on the image to be decoded during encoding.

3. The method according to claim 1 or 2, wherein the code table corresponding to the block to be decoded is selected from N code tables based on a code table index, wherein the code table index is obtained by decoding the bit stream.

4. The method according to claim 1 or 2, wherein the code table corresponding to the block to be decoded is selected from N code tables based on a characteristic of a coefficient of a neighboring block of said block to be decoded, wherein the characteristic of the coefficient is a characteristic of a coefficient of a high-frequency sub-band in the neighboring block, and the neighboring block and the block to be decoded are in the same high-frequency sub-band.

5. The method according to claim 4, wherein N code tables are classified into M code table groups, M≥2, M is a positive integer, and the code table corresponding to the block to be decoded is determined based on the target group of code tables, and the target group of code tables is selected from the M code table groups based on the characteristic of the coefficient of the neighboring block of said block to be decoded.

6. The method according to claim 5, wherein, when the number of code tables in the target code table group is greater than or equal to 2, the code table corresponding to the block to be decoded is selected from the target code table group based on a code table index obtained by decoding the bit stream.

7. The method according to claim 4, wherein the coefficient characteristic is the average value of the absolute values ​​of the decoded coefficients of the high-frequency sub-range in the adjacent block, or the largest value of the absolute values ​​of the coefficients of the high-frequency sub-range, or the median of the absolute values ​​of the coefficients of the high-frequency sub-range.

8. The method according to any one of claims 4 to 7, wherein the neighboring block is at least one of a top block, a left block, and an upper left block, which belong to the block to be decoded and which are in the high frequency sub-band, or the neighboring block is a previous block, which belongs to the block to be decoded and which is in the high frequency sub-band.

9. The method according to any one of claims 1 to 8, wherein the bit stream comprises a syntax structure corresponding to a block to be decoded, wherein the syntax structure comprises a syntax element indicating a code table index, and the code table index is an index of a code table corresponding to the block to be decoded.

10. The method according to any one of paragraphs 1-9, in which the N code tables include the following first code table: the number prefix0Count of zeros in the prefix code corresponding to the absolute value of the first coefficient whose coefficient amplitude is greater than 3 in the first code table satisfies prefix0Count=FastLog2(abs(v)-2)+5; and the number of suffix bits corresponding to the absolute value of the first coefficient whose coefficient amplitude is greater than 3 in the first code table satisfies prefix0Count-5.

11. The method according to any one of paragraphs 1-10, in which the N code tables include the following second code table: the number prefix1Count of ones in the prefix code corresponding to the absolute value of the second coefficient whose coefficient amplitude is greater than 5 in the second code table satisfies prefix1Count=FastLog2(abs(v)-4)+4; and the number of suffix bits corresponding to the absolute value of the second coefficient whose coefficient amplitude is greater than 5 in the second code table satisfies prefix1Count-4.

12. The method according to any one of paragraphs 1-11, in which the N code tables include the following third code table: the number of prefix2Count ones in the prefix code corresponding to the absolute value of the third coefficient whose coefficient amplitude is greater than 6 in the third code table satisfies prefix2Count=FastLog2(abs(v)-5)+2; and the number of suffix bits corresponding to the absolute value of the third coefficient whose coefficient amplitude is greater than 5 in the third code table satisfies prefix2Count-2.

13. The method according to any one of paragraphs 1-12, in which N code tables include a fourth code table: the number prefix3Count of ones in the prefix code corresponding to the absolute value of the fourth coefficient whose coefficient amplitude is greater than 31 in the fourth code table satisfies prefix1Count=FastLog2(abs(v))-2; and the number of suffix bits corresponding to the absolute value of the fourth coefficient whose coefficient amplitude is greater than 5 in the fourth code table satisfies prefix3Count+2.

14. A coding method comprising the steps of: obtaining a code table corresponding to a block to be encoded in an image to be encoded, wherein the block to be encoded is a block of coefficients in a high-frequency sub-band obtained by performing a wavelet transform on the image to be encoded, wherein the code table is a code table selected from N code tables, wherein the N code tables correspond to different probability distributions of the amplitudes of the coefficients of the high-frequency sub-band, N is a positive integer and N≥2; and encoding a block to be encoded based on a code table corresponding to the block to be encoded to obtain a bit stream.

15. The method of claim 14, wherein the code table corresponding to the block to be encoded is a code table selected from N code tables and corresponding to the smallest bit cost of N bit costs, wherein the N bit costs are predicted by encoding the block to be encoded individually based on the N code tables.

16. The method according to claim 14, wherein a code table corresponding to a block to be coded is selected from N code tables based on a characteristic of a coefficient of a neighboring block of said block to be coded, wherein the characteristic of the coefficient is a characteristic of a coefficient of a high-frequency sub-band in the neighboring block, and the neighboring block and the block to be coded are in the same high-frequency sub-band.

17. The method according to claim 16, wherein N code tables are classified into M code table groups, M≥2, M is a positive integer, and the code table corresponding to a block to be encoded is determined based on a target group of code tables, and the target group of code tables is selected from the M code table groups based on a characteristic of a coefficient of a neighboring block of said block to be encoded.

18. The method according to claim 17, wherein, when the number K of code tables in the target group of code tables is greater than or equal to 2, the code table corresponding to the block to be coded is a code table selected from the target group of code tables and corresponding to the smallest bit cost of K bit costs, wherein the K bit costs are predicted bit costs obtained by encoding the block to be coded individually based on the K code tables in the target group of code tables, where K is a positive integer.

19. The method according to any one of paragraphs 16-18, in which the coefficient characteristic is the average value of the absolute values ​​of the coefficients of the high-frequency sub-range in the adjacent block, or the greatest value of the absolute values ​​of the coefficients of the high-frequency sub-range, or the median of the absolute values ​​of the coefficients of the high-frequency sub-range.

20. The method according to any one of claims 16 to 19, wherein the neighboring block is at least one of a top block, a left block, and an upper left block, which belong to the block to be encoded and which are in the high frequency sub-band, or the neighboring block is a previous block, which belongs to the block to be encoded and which is in the high frequency sub-band.

21. The method according to any one of claims 14 to 20, wherein the bit stream comprises a syntactic structure corresponding to a block to be encoded, wherein the syntactic structure comprises a syntax element indicating a code table index, and the code table index is an index of a code table corresponding to the block to be encoded.

22. An encoder containing: a memory and a processor, wherein the memory is coupled to the processor; and the memory stores program instructions, and when the program instructions are executed by the processor, the processor is ensured to perform the steps of the method according to any one of paragraphs 14-21.

23. A decoder comprising: a memory and a processor, wherein the memory is coupled to the processor; and the memory stores program instructions, and when the program instructions are executed by the processor, the processor is ensured to perform the steps of the method according to any one of claims 1-13.

24. An encoder comprising a processing circuit that implements the steps of the method according to any one of paragraphs 14-21.

25. A decoder comprising a processing circuit that implements the steps of the method according to any one of claims 1-13.

26. A machine-readable storage medium, wherein the machine-readable storage medium stores a computer program, and when the computer program is run on a computer or a processor, the computer or processor is enabled to execute the method according to any one of paragraphs 1-13, or the computer or processor is enabled to execute the method according to any one of paragraphs 14-21.

27. A computer program product, wherein the computer program product comprises computer instructions, and when the computer instructions are executed by a computer or a processor, the steps of the method according to any one of claims 1-13 are performed or the steps of the method according to any one of claims 14-21 are performed.

28. A machine-readable storage medium, wherein the machine-readable storage medium stores a bit stream generated using the method according to any one of paragraphs 14-21.