# US 10,313,688 B2 · Image coding method, image decoding method, image coding apparatus, image decoding apparatus, and image coding and decoding apparatus

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- Number: US 10,313,688 B2
- Document ID: US10313688B2
- Status: Granted
- Kind: B2
- Application number: 16/046,348
- Filed: 2018-07-26
- Published: 2018-11-22
- Granted: 2019-06-04
- Earliest claimed: 2012-09-10
- Assignees: Sun Patent Trust
- Applicants: Sun Patent Trust
- Inventors: Kengo Terada; Youji Shibahara; Kyoko Tanikawa; Hisao Sasai; Toshiyasu Sugio; Toru Matsunobu
- Web page: https://patentgrep.com/patent/US10313688B2

## CPC

- H04N 19/186: the unit being a colour or a chrominance component
- G06T 9/007: {Transform coding, e.g. discrete cosine transform}
- H04N 19/119: Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
- H04N 19/122: Selection of transform size, e.g. 8x8 or 2x4x8 DCT; Selection of sub-band transforms of varying structure or type
- H04N 19/136: Incoming video signal characteristics or properties
- H04N 19/137: Motion inside a coding unit, e.g. average field, frame or block difference
- H04N 19/157: Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
- H04N 19/176: the region being a block, e.g. a macroblock
- H04N 19/60: using transform coding
- H04N 19/61: in combination with predictive coding
- H04N 19/70: characterised by syntax aspects related to video coding, e.g. related to compression standards
- H04N 19/96: Tree coding, e.g. quad-tree coding
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

An image coding method in which a chroma component and a luma component of an input image including one or more transform blocks are transformed to code the input image. The luma component has the same size as the current transform block. The chroma component is smaller than the current transform block. In the method, when the current transform block has a first minimum size, the chroma component is transformed on a basis of a block resulting from binding a plurality of the chroma blocks to has the same size as the luma block, and when the current transform block has a size other than the first minimum size, a CBF flag indicating whether or not coefficients of the chroma component include a non-zero coefficient is not coded.

## Claims

### Claim 1

An image decoding method of decoding an image from a coded bitstream,
the image including a coding block,
the coding block including one or more transform blocks each having a luma component and a chroma component,
the luma component being to be processed on a basis of a luma block which belongs to a current one of the one or more transform blocks and has a same size as a size of the current transform block,
the chroma component being to be processed on a basis of a chroma block which belongs to a current one of the one or more transform blocks and has a size smaller than a size of the luma block, and
the image decoding method comprising:
decoding coefficients of the luma component and coefficients of the chroma component which are coded and included in the coded bitstream; and
deriving the luma component by performing transform on the coefficients of the luma component and deriving the chroma component by performing transform on the coefficients of the chroma component,
wherein in the deriving,
a value of CU Layer parameter is derived, the CU Layer parameter indicating a level of splitting the coding block,
a value of TU Layer parameter is derived, the TU Layer parameter indicating a level of splitting the current transform block, and
when a sum of the value of the CU Layer parameter and the value of the TU Layer parameter is four, the chroma component is derived by performing the transform on the coefficients of the chroma component on a basis of a block resulting from binding a plurality of the chroma blocks, the resulting block having a same size as the size of the luma block, and
in the decoding, when the size of the current transform block is a size other than a first minimum size, a flag indicating whether or not the coefficients of the chroma component include a non-zero coefficient is decoded.

### Claim 2

An image decoding device for decoding an image from a coded bitstream,
the image including a coding block,
the coding block including one or more transform blocks each having a luma component and a chroma component,
the luma component being to be processed on a basis of a luma block which belongs to a current one of the one or more transform blocks and has a same size as a size of the current transform block,
the chroma component being to be processed on a basis of a chroma block which belongs to a current one of the one or more transform blocks and has a size smaller than a size of the luma block, and
the image decoding device comprising:
circuitry; and
a memory coupled to the circuitry;
wherein the circuitry, in operation, performs the following using the memory:
decoding coefficients of the luma component and coefficients of the chroma component which are coded and included in the coded bitstream; and
deriving the luma component by performing transform on the coefficients of the luma component and deriving the chroma component by performing transform on the coefficients of the chroma component,
wherein in the deriving,
a value of CU Layer parameter is derived, the CU Layer parameter indicating a level of splitting the coding block,
a value of TU Layer parameter is derived, the TU Layer parameter indicating a level of splitting the current transform block, and
when a sum of the value of the CU Layer parameter and the value of the TU Layer parameter is four, the chroma component is derived by performing the transform on the coefficients of the chroma component on a basis of a block resulting from binding a plurality of the chroma blocks, the resulting block having a same size as the size of the luma block, and
in the decoding, when the size of the current transform block is a size other than a first minimum size, a flag indicating whether or not the coefficients of the chroma component include a non-zero coefficient is decoded.