Image coding apparatus, method for coding image, program therefor, image decoding apparatus, method for decoding image, and program therefor

Patent metadata

Field	Value
Publication number	US-9277221-B2
Application number	US-201214003776-A
Country	US
Kind code	B2
Filing date	Feb 27, 2012
Priority date	Mar 9, 2011
Publication date	Mar 1, 2016
Grant date	Mar 1, 2016

Abstract

An image processing apparatus includes a division unit configured to divide an input image into a plurality of subblocks subjected to quantization control a subblock quantization parameter calculation unit configured to calculate a quantization parameter of each of the subblocks, a basic block quantization parameter calculation unit configured to set a basic block including at least two subblocks and to calculate a quantization parameter of the basic block, a difference value calculation unit configured to calculate a difference value between the quantization parameter of the basic block and the quantization parameter of each subblock included in the basic block, and a difference value coding unit configured to code the difference value.

First claim

The invention claimed is:

1. An image coding apparatus comprising:
a first acquisition unit configured to acquire a first difference value between a first quantization parameter of a first subblock and a second quantization parameter of a second subblock, where the first subblock and the second subblock are in a block;
a second acquisition unit configured to acquire a second difference value between a third quantization parameter of a third subblock in the block and a value based on an average of quantization parameters of subblocks in the block; and
a coding unit configured to code the first difference value and the second difference value.

2. The image coding apparatus according to claim 1 , wherein the first acquisition unit acquires the first difference value between the first quantization parameter of the first subblock and the second quantization parameter of the second subblock adjacent to the right of the first subblock.

3. The image coding apparatus according to claim 1 , wherein the second acquisition unit acquires the second difference value between the third quantization parameter of the third subblock adjacent below the second subblock and the value based on the average of at least two of: the first quantization parameter of the first subblock, the second quantization parameter of the second subblock, and a quantization parameter of another subblock in the block.

4. An image decoding apparatus comprising:
a decoding unit configured to decode coded data related to a difference value between a quantization parameter of a subblock on which quantization control is performed and a predetermined parameter, and to generate the difference value;
a first acquisition unit configured to acquire, based on a first quantization parameter of a first subblock as the predetermined parameter and the difference value generated by the decoding unit, a second quantization parameter of a second subblock, where the first subblock and the second subblock are in a block; and
a second acquisition unit configured to acquire, based on the difference value generated by the decoding unit and a value based on an average of quantization parameters of subblocks in the block as the predetermined parameter, a third quantization parameter of a third subblock in the block.

5. A method for coding an image in an image coding apparatus, the method comprising:
acquiring a first difference value between a first quantization parameter of a first subblock and a second quantization parameter of a second subblock, where the first subblock and the second subblock are in a block;
acquiring a second difference value between a third quantization parameter of a third subblock in the block and a value based on an average of quantization parameters of subblocks in the block; and
coding the first difference value and the second difference value.

6. A method for decoding an image in an image decoding apparatus, the method comprising:
decoding coded data related to a difference value between a quantization parameter of a subblock on which quantization control is performed and a predetermined parameter, and generating the difference value;
acquiring, based on a first quantization parameter of a first subblock as the predetermined parameter and the generated difference value, a second quantization parameter of a second subblock, where the first subblock and the second subblock are in a block; and
acquiring, based on the generated difference value and a value based on an average of quantization parameters of subblocks in the block as the predetermined parameter, a third quantization parameter of a third subblock in the block.

7. The image coding apparatus according to claim 1 ,
wherein the first acquisition unit acquires the first difference value between the first quantization parameter of the first subblock, the first subblock located at an upper left end among the subblocks included in the block, and the second quantization parameter of the second subblock.

8. The image coding apparatus according to claim 1 ,
wherein the first acquisition unit acquires the first difference value between the first quantization parameter of the first subblock, which is an initial subblock to be quantized in the block, and the second quantization parameter of the second subblock.

9. The image decoding apparatus according to claim 4 ,
wherein the first acquisition unit acquires the second quantization parameter of the second subblock adjacent to the right of the first subblock based on the first quantization parameter of the first subblock and the difference value generated by the decoding unit.

10. The image decoding apparatus according to claim 4 ,
wherein the second acquisition unit acquires the third quantization parameter of the third subblock adjacent below to the second subblock based on the difference value generated by the decoding unit and the value based on the average of at least two of: the first quantization parameter of the first subblock, the second quantization parameter of the second subblock, and a quantization parameter of another subblock in the block.

11. The image decoding apparatus according to claim 4 ,
wherein the first acquisition unit acquires the second quantization parameter of the second subblock based on the first quantization parameter of the first subblock, which is an initial subblock to be dequantized in the block, and the difference value generated by the decoding unit.

12. A non-transitory computer-readable medium having computer executable instructions stored thereon, which when loaded into a computer and executed perform a method for controlling an image coding apparatus, the method comprising:
acquiring a first difference value between a first quantization parameter of a first subblock and a second quantization parameter of a second subblock, where the first subblock and the second subblock are in a block;
acquiring a second difference value between a third quantization parameter of a third subblock in the block and a value based on an average of quantization parameters of subblocks in the block; and
coding the first difference value and the second difference value.

13. A non-transitory computer-readable medium having computer executable instructions stored thereon, which when loaded into a computer and executed perform a method for controlling an image decoding apparatus, the method comprising:
decoding coded data related to a difference value between a quantization parameter of a subblock on which quantization control is performed and a predetermined parameter, and generating the difference value;
acquiring, based on a first quantization parameter of a first subblock as the predetermined parameter and the generated difference value, a second quantization parameter of a second subblock, where the first subblock and the second subblock are in a block; and
acquiring, based on the generated difference value and a value based on an average of quantization parameters of subblocks in the block as the predetermined parameter, a third quantization parameter of a third subblock in the block.

14. The image coding apparatus according to claim 1 , wherein the second acquisition unit acquires the second difference value between the third quantization parameter of the third subblock and the average of quantization parameters of subblocks in the block.

15. The image coding apparatus according to claim 1 , further comprising
a first calculation unit configured to calculate a difference value between the first quantization parameter of the first subblock and the second quantization parameter of the second subblock; and
a second c

Assignees

• Maeda Mitsuru
• Canon Kk

Inventors

• Maeda Mitsuru

Classifications

• H04N19/61

  in combination with predictive coding · CPC title

• H04N19/167

  Position within a video image, e.g. region of interest [ROI] · CPC title

• H04N19/176

  the region being a block, e.g. a macroblock · CPC title

• H04N19/91

  Entropy coding, e.g. variable length coding [VLC] or arithmetic coding · CPC title

• H04N19/50 Primary

  using predictive coding (H04N19/61 takes precedence) · CPC title