Apparatus and method for coding image, and non-transitory computer readable medium thereof

Patent metadata

Field	Value
Publication number	US-9407918-B2
Application number	US-201213593664-A
Country	US
Kind code	B2
Filing date	Aug 24, 2012
Priority date	Jan 25, 2012
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

According to one embodiment, a prediction unit generates a prediction block to be used for prediction of a coding target block, based on at least one reference block adjacent to the coding target block in the image. Each number of pixels in the coding target block and the prediction block is a power of two. A calculation unit calculates a residual block having residual pixel values between the coding target block and the prediction block. A decision unit decides whether to code the residual block, based on pixel values of at least one of the coding target block, the reference block and the prediction block. A coding unit codes the residual block by variable length coding when the residual block is decided to be coded, and codes a skip flag representing the residual block not being coded when the residual block is not decided to be coded.

First claim

What is claimed is:

1. An apparatus for coding a coding target block in an input image, comprising:
a prediction unit, realized by a computer processor to execute programs stored on a memory device, configured to acquire the input image, and generate a prediction block to be used for prediction of the coding target block based on at least one reference block in the input image, each number of pixels in the coding target block and the prediction block being a power of two, the at least one reference block including at least one pixel included in the coding target block;
a calculation unit, realized by the computer processor, configured to calculate a residual block having residual pixel values between the coding target block and the prediction block;
a decision unit, realized by the computer processor, configured to decide whether to code the residual block, based on pixel values of at least one of the coding target block, the reference block and the prediction block;
a coding unit, realized by the computer processor, configured to code the residual block; and
a skip processing unit, realized by the computer processor, configured to count up the number of residual blocks not being continuously coded,
wherein
the at least one reference block is a plurality of reference blocks adjacent to the coding target block in the input image,
the decision unit decides not to code the residual block when pixel values of corresponding pixels among the plurality of reference blocks are equal and when a sum of absolute values of pixel values of the residual block is equal to “0”, and decides to code the residual block when pixel values of corresponding pixels among the plurality of reference blocks are not equal or when a sum of absolute values of pixel values of the residual block is not equal to “0”,
the skip processing unit counts up the number of residual blocks when a sum of pixel values of the residual block absolute values is equal to “0”, and codes the number of residual blocks which is counted up,
the coding unit codes the residual block by variable length coding when the residual block is decided to be coded, and codes the number of residual blocks when a sum of absolute values of pixel values of the residual block is not equal to “0”.

2. The apparatus according to claim 1 , further comprising:
a first count unit, realized by the computer processor, configured to count the number of residual blocks to skip coding; and
a second count unit, realized by the computer processor, configured to count the number of residual blocks to code by variable length coding;
wherein the coding unit respectively codes the number of residual blocks to skip coding and the number of residual blocks to code by variable length coding.

3. The apparatus according to claim 2 , wherein
the coding unit outputs in order, a plurality of coded data of the residual block by variable length coding, and a plurality of coded data of the number of residual blocks,
the plurality of coded data of the number of residual blocks includes coded data of the number of residual blocks to skip coding and coded data of the number of residual blocks to code by variable length coding, mutually aligned in correspondence with each block in the input image.

4. The apparatus according to claim 2 , wherein
the coding unit outputs in order, a plurality of coded data of the number of residual blocks, and a plurality of coded data of the residual block by variable length coding,
the plurality of coded data of the number of residual blocks includes coded data of the number of residual blocks to skip coding and coded data of the number of residual blocks to code by variable length coding, mutually aligned in correspondence with each block in the input image.

5. The apparatus according to claim 2 , further comprising:
an initial calculation unit, realized by the computer processor, configured to calculate an initial residual block including residual pixel values of corresponding pixels between the coding target block and a block starting a pixel adjacent to the coding target block in the input image;
wherein the decision unit decides whether to code the residual block, based on a sum of absolute values of the residual pixel values of the initial residual block.

6. The apparatus according to claim 1 , wherein
the prediction unit generates a plurality of prediction blocks,
the decision unit decides not to code the residual block when pixel values of corresponding pixels among the plurality of prediction blocks are equal, and decides to code the residual block when pixel values of corresponding pixels among the plurality of prediction blocks are not equal.

7. The apparatus according to claim 1 , further comprising:
a quantization unit, realized by the computer processor, configured to quantize the input image;
wherein the prediction unit accepts quantized pixel values of each block of the quantized image from the quantization unit.

8. A method for coding a coding target block in an input image, comprising:
acquiring the input image;
generating a prediction block to be used for prediction of the coding target block based on at least one reference block in the input image, each number of pixels in the coding target block and the prediction block being a power of two, the at least one reference block including at least one pixel included in the coding target block;
calculating a residual block having residual pixel values between the coding target block and the prediction block;
deciding whether to code the residual block, based on pixel values of at least one of the coding target block, the reference block and the prediction block;
coding the residual block; and
counting up the number of residual blocks not being continuously coded,
wherein
the at least one reference block is a plurality of reference blocks adjacent to the coding target block in the input image,
the deciding includes deciding not to code the residual block when pixel values of corresponding pixels among the plurality of reference blocks are equal and when a sum of absolute values of pixel values of the residual block is equal to “0”, and deciding to code the residual block when pixel values of corresponding pixels among the plurality of reference blocks are not equal or when a sum of absolute values of pixel values of the residual block is not equal to “0”,
the counting includes counting up the number of residual blocks when a sum of absolute values of pixel values of the residual block is equal to “0”, and coding the number of residual blocks which is counted up,
the coding includes coding the residual block by variable length coding when the residual block is decided to be coded, and coding the number of residual blocks when a sum of absolute values of pixel values of the residual block is not equal to “0”.

9. The method according to claim 8 , further comprising:
counting the number of residual blocks to skip coding; and
counting the number of residual blocks to code by variable length coding;
wherein the coding includes respectively coding the number of residual blocks to skip coding and the number of residual blocks to code by variable length coding.

10. The method according to claim 9 , further comprising:
outputting in order, a plurality of coded data of the residual block by variable length coding, and a plurality of coded data of the number of residual blocks;
wherein the plurality of coded data of the number of residual blocks includes coded data of the number of residual blocks to skip coding and coded data of the number of residual blocks to code by variable length coding, mutually aligned in correspondence with each block in the input image.

Assignees

• Matsumura Atsushi
• Koto Shinichiro
• Toshiba Kk

Inventors

• Matsumura Atsushi
• Koto Shinichiro

Classifications

• H04N19/137 Primary

  Motion inside a coding unit, e.g. average field, frame or block difference · CPC title

• H04N19/132

  Sampling, masking or truncation of coding units, e.g. adaptive resampling, frame skipping, frame interpolation or high-frequency transform coefficient masking · CPC title

• H04N19/91

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

• H04N19/50

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

• H04N19/103

  Selection of coding mode or of prediction mode · CPC title