Complexity reduction of significance map coding

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.

What is claimed is: 
     
         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. 
   
     
     
         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.