Pools of transforms for local selection of a set of transforms in video coding

Abstract

A method and apparatus for improving the performance of video encoders and decoders involves selecting a set of transforms from among a plurality of sets of transforms that can be used for coding blocks in a region of a video image. Within a region, selection of a particular transform from among a plurality of transforms comprising the selected set of transforms is used to encoder or decode at least one block in the region. Associated indices representing the set of transforms to be used within a region and the selected transform for a block can be sent in a bitstream. In an alternate embodiment, a default set of transforms is complemented by selection of an additional set of transforms on a block or region basis.

Description

technical field [0001] The present principles relate to video compression, and more specifically to performing video encoding and decoding using block transforms. Background technique [0002] Many attempts have been made to improve the transformation of block-based codecs. They can be classified into two categories. [0003] The first category is the change that transforms itself. The most sophisticated methods use the learning of transformations on the actual content. [0004] The second category is to let several transformations compete at the local level (eg, block level). [0005] The combination of the two types of transform changes leads to a so-called "multiple adaptive transform" scheme. Additional syntax may be required to identify which of multiple transforms is to be used by the block. [0006] Although at the cost of additional syntax, local flexibility in transform selection has been shown to have a positive impact on compression schemes. [0007] In the ...

AI Technical Summary

Problems solved by technology

However, adding many transforms may degrade performance, since the extra signaling destroys any gains gained from better compression of the transform coefficients

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