# US 2021/0243464 A1 · Complexity reduction of significance map coding

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- Number: US 2021/0243464 A1
- Document ID: US20210243464A1
- Status: Published application
- Kind: A1
- Application number: 17/237,352
- Filed: 2021-04-22
- Published: 2021-08-05
- Earliest claimed: 2012-01-20
- Assignees: Sony Group Corporation
- Applicants: Sony Group Corporation
- Inventors: CHEUNG AUYEUNG
- Web page: https://patentgrep.com/patent/US20210243464A1

## CPC

- H04N 19/46: Embedding additional information in the video signal during the compression process (H04N19/517, H04N19/68, H04N19/70 take precedence)
- H04N 19/463: by compressing encoding parameters before transmission
- H04N 19/91: Entropy coding, e.g. variable length coding [VLC] or arithmetic coding
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

The complexity of coding a significant_coeff_flag in video coding such as High Efficiency Video Coding (HEVC) is able to be reduced using the same mapping to select luma and chroma contexts for the coding of 4×4 significant maps. As a result, a 15 element lookup table and multiple branches are able to be removed to select the context index, and WD text is also simplified.

## Claims

### Claim 1

An encoding apparatus, comprising:
an encoding unit configured to encode a significance map for 4*4 blocks of quantized transform coefficients, based on a mapping of an index of the quantized transform coefficients and a context index for assignment of contexts to a luma component of the 4*4 blocks of the quantized transform coefficients and to a chroma component of the 4*4 blocks of the quantized transform coefficients, wherein
the mapping of the index of the quantized transform coefficients corresponds to a common context index for indices of the quantized transform coefficients in a respective grouping of a plurality of groupings of the indices of the quantized transform coefficients, and
the plurality of groupings of the indices of the quantized transform coefficients is same for the 4*4 blocks of the quantized transform coefficients of the luma component and for the 4*4 blocks of the quantized transform coefficients of the chroma component.

### Claim 2

A method, comprising:
in an encoding apparatus:
encoding a significance map for 4*4 blocks of quantized transform coefficients, based on a mapping of an index of the quantized transform coefficients and a context index for assignment of contexts to a luma component of the 4*4 blocks of the quantized transform coefficients and to a chroma component of the 4*4 blocks of the quantized transform coefficients, wherein
the mapping of the index of the quantized transform coefficients corresponds to a common context index for indices of the quantized transform coefficients in a respective grouping of a plurality of groupings of the indices of the quantized transform coefficients, and
the plurality of groupings of the indices of the quantized transform coefficients is same for the 4*4 blocks of the quantized transform coefficients of the luma component and for the 4*4 blocks of the quantized transform coefficients of the chroma component.