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JVET-D0124 EE9/AHG7: On De-quantization and Scaling for Extended Colour Volume Materials [J. Zhao, S.-H. Kim, K. Misra, A. Segall (Sharp)] [late]
Discussed in BoG D0192 (chaired by A. Segall)
This contribution provides information relevant to the EE9 and AHG7 activities on Extended Colour Volume material. Specifically, the document considers three topics: First, it reports on the potential anchor configuration that was released as part of the EE9 activities. Second, it describes a generalization of the weighted PSNR calculation that was proposed in JVET-C0095, with the asserted benefit of being applicable to testing scenarios. Third, it provides updated results for the de-quantization and scaling methods. The results show that the proposed method has a weighted BD-Rate gain of approximately 1.47% and 1.83% compared to explicit signalling of the delta QP. It was proposed to study these issues in continued AHG and EE activities.
Three topics were addressed.
- First, potential improvement of the anchors relatively to the candidate software of EE9 where the QP is a function (more precisely a LUT) of the luminance at a CTU level, using the DeltaQP syntax to signal it in the stream. The proposal is to change the granularity from CTU level to a lower level. Tests have reportedly shown that the best trade-off is obtained by depth=1 for the extra granularity.
- Second, a new weighted PSNR is introduced by weighting each sample by a weight that depends on the deltaQP. The chroma weight is taken the same as the luma weight.
- Third, new results are presented by
- not using the deltaQP syntax anymore
- adding the weight (associated to the new PSNR metric) in the RDO of the encoder that chooses the block splitting.
Gains of about 1.5% were reported using the new weighted metric, compared to the anchor using the deltaQP syntax.
It was proposed to further explore the new metric in relevant future EE/AhG’s.