In-loop colour-space-transform coding based on integered SVD for HEVC range extensions

Inter colour-component correlation is generally very high in RGB 4:4:4 chroma format. To improve the coding performance of the high efficiency video coding (HEVC) especially for such content, we propose the in-loop colour-space-transform. The colour space is dynamically transformed into un-correlated space by employing singular value decomposition (SVD) for each block at both the encoder and decoder. Signals in transformed colour space are coded with the existing intra / inter coding framework. We utilize the simplified SVD process implemented only by integer operations for the complexity reduction. Compared with HM10.0 as an anchor method, BD-bitrate gain reached 23.8% and 23.4% for the all intra case and the random access case, respectively, while a runtime of the decoder increase 4.8-9.8%.