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42nd Meeting: Santa Eulària, ES, April 2026 2026-04-25 11:49
Non-EE2: A bugfix of the subsampling filter for certain CCLM/CCCM tools
Authors: Takeshi Chujoh KDDI H. Kato KDDI yoshitaka kidani KDDI K. Kawamura KDDI
Abstract
In this contribution, a 4:4:4-to-4:2:0 subsampling filter is improved for certain CCLM/CCCM tools in the ECM-19.1 software. At the Geneva meeting in October 2025, experiments on adaptive subsampling filter selection were conducted; however, they didn't include the case where ChromaLocType is equal to 2 (top-left position) for HDR sequences. Therefore, this contribution improves it and reports the experimental results. As a result, the coding efficiency for HDR sequences has been improved without increasing the encoding and decoding times.
Meeting Notes
JVET-AP0105 Non-EE2: A bugfix of the subsampling filter for certain CCLM/CCCM tools [T. Chujoh, H. Kato, Y. Kidani, K. Kawamura (KDDI)]

In this contribution, a 4:4:4-to-4:2:0 subsampling filter is improved for certain CCLM/CCCM tools in the ECM-19.1 software. At the Geneva meeting in October 2025, experiments on adaptive subsampling filter selection were conducted; however, they didn't include the case where ChromaLocType is equal to 2 (top-left position) for HDR sequences. Therefore, this contribution improves it and reports the experimental results. As a result, the coding efficiency for HDR sequences has been improved without increasing the encoding and decoding times.

This would modify the implementation of some existing tools such that they would work as intended for ChromaLocType equal to 2, and improve performance for HDR sequences.

Decision (BF/SW): Adopt JVET-AP0105. (no change in CTC, HDR is not part of CTC).

Cited:
JVET-AP0199 X JVET-AQ0006 JVET-AQ0101
ARCHIVE :
JVET-AP0105-v1.docx JVET-AP0105-v1.pdf JVET-AP0105-v1.xlsm
Decisions
adopted
Decision (BF/SW): Adopt JVET-AP0105. (no change in CTC, HDR is not part of CTC).
Citation