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Colour-related SEI and VUI (3)The type of contributions in this area was summarized as:
14.1.97.1.1.1.1.1.340JCTVC-P0050 HLS: SEI message for Knee Function Information [S. Hattori, O. Nakagami, T. Suzuki (Sony)] Presented 01-14 (GJS). This contribution proposes a new SEI message to signal knee function information to enable display devices to process decompression or compression of colour samples of the decoded pictures to customize the picture for a particular display environment. The idea was initially proposed in JCTVC-O0064. This contribution made two modifications to the proposal in JCTVC-O0064. 1) The syntax and semantics are enhanced to provide enable flexibility to the characteristics of knee function parameters. 2) Two options on how to integrate the proposed syntax and semantics as SEI messages are provided. The first option is to define a new SEI message dedicated for the knee function information. The second option is to extend the existing tone mapping information SEI message to define knee function information as another model of mapping function. It was noted, per parent-body guidance, that a new SEI message would be more appropriate than extending the prior tone mapping SEI message. Otherwise, this could be identified as another tone mapping SEI message model. Some editorial concern was expressed regarding use of "compression" term. It was asked whether the (0, 0) and (1, 1) points are implied and do not need to be sent or are actually sent. The proposed semantics already included a constraint to prohibit sending these values, so they are implicit. Several participants expressed support for the proposal and indicated that they had studied it and understood its use. It was planned to adopt this (as a new SEI message), pending confirmation of no concerns at the parent-body level. Decision: Adopted (after parent-level confirmation). 14.1.97.1.1.1.1.1.341JCTVC-P0084 Indication of SMPTE 2084, 2085 and carriage of 2086 metadata in HEVC [C. Fogg (Harmonic), J. Helman (Movielabs)] Presented 01-14 (GJS). This is partly a VUI proposal and partly an SEI message proposal. The proponent indicated that this is related to P0050. The contribution proposes text changes in the HEVC specification to support metadata indicators for three SMPTE standards and the direct coding of XYZ. In Annex E, video usability information (VUI) changes are proposed for: (1) indication of SMPTE ST 428-1 ("CIE XYZ in Digital Cinema") with a new colour_primaries Table E-3 entry; (2) indication of SMPTE ST 2084 ("Electro-Optical Transfer Function for High Dynamic Range Reference Displays") with a new transfer_characteristcs Table E-4 entry; and (3) indication of direct XYZ (YZX in planar order) with a new matrix_coeffs Table E-5 entry. In Annex D, a new SEI message was proposed for carriage of SMPTE ST 2086 ("Mastering Display Colour Volume Metadata for High Luminance and Wide Colour Gamut Images") metadata. Support for all four metadata are independent of each other. In discussion, it was clarified that intent is for the bit depth should be constrained to greater than or equal to 10 and the bit depth variable use should be defined as with other values and that the full range flag should be constrained to be equal to 0 and the chroma format should be constrained to 4:4:4 and the luma and chroma bit depths should be equal with the proposed definition. The SEI message is proposed to have persistence in output order (and likely to have, but not necessarily to have whole-CVS scope). It was remarked by the SMPTE liaison representative that the referenced SMPTE standards are either already fully approved or expected to have final approval in SMPTE prior to the timing of ISO/IEC FDAM and ITU-T Consent, depending on the particular standard in question, and that they are intended for such a compressed-bitstream usage (among other uses). The representative also indicated that a more formal liaison communication could be expected by the next meeting. It was remarked that this topic is related to work ongoing at the parent-body level. Aside from that, no significant issues were identified. Decision: Adopted (after parent-level discussion). This action is taken under the assumption that the corresponding standards in SMPTE will have final approval prior to final approval in ITU-T/ISO/IEC. 14.1.97.1.1.1.1.1.342JCTVC-P0126 SEI message for Colour Mapping Information [P. Andrivon, P. Bordes, E. François (Technicolor)] Presented 01-14 (GJS). This contribution discusses colour mapping in regard to colour space transition relating to upcoming HDTV and UHDTV services deployment. Additionally, it is claimed that colour mapping metadata helps preserve the artistic intent of the content producer while maintaining differentiation between display manufacturers. Some concerns had previously been expressed on the complexity of a 3D LUT model. A simplified colour mapping model based on 1D LUT and 3x3 matrix was proposed in order to alleviate processing complexity and to leverage CE devices computational resources. The proponent asserted that current-generation display devices have appropriate built-in capability to use such information. The proposal is asserted to be similar in concept (and in syntax and semantics) to the current tone mapping SEI message type 3 but extended to support one LUT per channel instead of just one LUT that applies to all three channels, and a matrix is also proposed for cross-component transformation. At the decoder side, the LUT would applied first, followed by the matrix (in the opposite order ordinarily used, e.g. for YUV to RGB to linear conversion). It was remarked that persistence aspects would need to be studied for this and the other colour-related proposed SEI messages. The proponent said that the persistence is similar to the tone mapping information SEI message. Some editorial concerns were expressed about the proposed text. Some additional study was requested by some participants, although there was some support for the proposal (at least in concept). No particular problems were identified with the proposal. Further study was encouraged.
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