JCTVC-M0418 Cross-check of adaptive inter-plane prediction for RGB content by HHI (JCTVC-M0230) [S. H. Kim, A. Segall (Sharp)] [late] [miss]
JCTVC-M0435 Cross-check of ‘Non-RCE1/Non-RCE2/AHG5/AHG8: Adaptive Inter-Plane Prediction for RGB Content’ (M0230) by Fraunhofer HHI [C. Rosewarne, M. Maeda (Canon)] [late] [miss]
JCTVC-M0447 Cross-check of Adaptive Inter-Plane Prediction for RGB Content in JCTVC-M0230 [W.-S. Kim (Qualcomm)] [late]
JCTVC-M0072 AHG7: Modification of in-loop colour-space transformation [S. Matsuo, M. Matsumura, S. Takamura, H. Fujii, A. Shimizu (NTT)]
This document introduces a modification of in-loop colour-space transformation of residual signals. To reduce the redundancy among the Y-Cb-Cr/R-G-B components, a colour-space transformation method was proposed in the contribution of JCTVC-L0371 (updated in M0411). In this contribution, to prevent the deterioration of the coding performance of L0371 and to speed up the run-times, the transformation is adaptively applied to residual signals using an eigenvalue derived by the calculation process of transformation matrices. The overall average coding gains against the anchor (HM10.0 RExt2.0) were 9.8% / 8.1% / 11.5% (AI High-tier), 11.2% / 7.4% / 12.7% (RA High-tier), and 11.1% / 5.8% / 12.7% (LD High-tier). The average run-times of encoding and decoding were 103.2% and 106.2%, respectively.
M0411 modifies the colour transform per CU, using adaptively collected statistics without sending syntax. This proposal modifies that scheme by establishing conditions (on a CU basis) for which the colour transformation is switched off.
A significant amount of processing is involved – some of which use high bit depths.
On average there is less gain than the M0411 scheme, but maximum losses are reduced.
For coding YUV content, some gains and some losses were observed.
It was asked whether offsets of chroma QP were tested. The contributor said they had tried some limited experimentation with that and had not found much of an effect.
It was suggested to have switching to just one colour transformation or a small set of transformations rather than the general approach.
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