JVET-E0069 AHG7/EE6: Comments on JVET common test conditions and evaluation procedures for HDR/WCG video [D. Rusanovskyy, A. K. Ramasubramonian, J. R. Sole, M. Karczewicz (Qualcomm)] [late]

The document provided comments on the JVET HDR/WCG CTC, HDR video test content, object and visual quality assessment procedures. As part of the document, an evaluation of candidate HDR sequences was considered. Several monitors were used during the evaluation, and some concerns with each configuration were identified.

The proponent commented that if the sequences were adapted to 1,000 cd/m², then it would be possible to use a consumer display. Otherwise, it was reported that the display would process the content with noticeable post-processing that may include clipping.

The proponent proposed using an HDR displays capable of 1,000 cd/m² and, specifically, a Sony BVM-X300.

The proponent also proposed to use a display adaptation, or tone mapping, process for viewing. This would be applied after decoding. It was requested for the AhG to consider the selection of display adaptation.

One participant expressed that it would be desirable if the RGB metrics could be removed from the evaluation.

One participant suggested that we should check the gamut of the original input.

The proponent also provided comments for 7 HDR sequences under study.

One participant commented that FireEater should be removed from the current test set.

There was a discussion about the use of apply display adaptation for viewing the HDR content. The approach was asserted to allow the use of a display with a peak brightness of 1,000 cd/m² to be used to evaluate content with a peak brightness of 4,000 cd/m².

Various options were then discussed and captured below:

1. Provide the 4,000 cd/m² content to the display and allow the display to tone map.
2. Apply an adaptation process prior to sending the content to the display.
3. Crop the UHD sequences to HD and display on the SIM2.
4. Downsample the UHD sequences to HD and display on the SIM2.
5. Limit the test sequences to 1,000 cd/m², which could be derived from the current 4,000 cd/m² sequences.
6. Create a content set that is limited to 1,000 cd/m². And, a second content set greater than 1,000 cd/m².
7. Create content sets divided by display characteristics.
8. Limit test sequences to the second “Table 2” category of the candidate sets.

One comment related to option 3 and 4 was that the SIM2 gamut may be smaller than the gamut of the content available, and so the device may perform gamut mapping and/or display adaptation.

One comment related to option 3 and 4 was that values outside the SIM2 gamut could be clipped.

One comment related to option 2 was that the adaptation process could be one defined in BT.2390.

For displays, it was suggested that there may be two general classes of displays available:

1. UHD displays with 1,000 cd/m² peak brightness and a gamut larger than BT.709
2. HD display with 4,000 cd/m² peak brightness with BT.709 gamut

One participant remarked that one way forward was to only use a category 1 display for visual evaluation and then modify the decoded output for display on a category 1 device. This modification could be a form of post-processing. It was further clarified that objective metrics would still use the unmodified decoded output.

One participant remarked that another way forward was to have test sequences that satisfied the limits of each display category. This could include considering some sequences that satisfy the limits of a category 1 display and other sequences that satisfy the limits of a category 2 display.

It was commented that some of the new HDR content available to the group is close to HD resolution and the effect of cropping is anticipated to be small.

Recommendation: HDR/WCG CTC may be updated to include HD HDR content at this meeting.

Recommendation: Further study of the visual evaluation and/or rendering of UHD, 4,000 cd/m² and wide colour gamut content should be studied in an AhG.

Recommendation: Request content providers if it is possible to provide HD HDR versions of the sequences. We note that for UHD sequences currently available, it might be useful to view the UHD sequences at this meeting.

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