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Interest in TPAC meeting to discuss SDR/HDR compositing issues

Is there any interest in meeting to discuss use cases and issues involved in compositing a mix of SDR and HDR elements: images, graphics and video? Examples would include maintaining the color levels of sRGB elements when a HDR video begins playback, subtitle levels on HDR video, mixing of sRGB and HDR images on a page and css support for HDR.

I have requested the 15:30 to 17:30 time slot on Tuesday 7 November in the community group room at TPAC for a possible discussion session among interested parties. (Many time slots had already been allocated so I went ahead and secured one before the where gone.)

Paul Kerr

2 Responses to Interest in TPAC meeting to discuss SDR/HDR compositing issues

  • Sounds good to me. I’d be happy to summarise the existing work done on this in TTWG for TTML2.


  • Good session yesterday, minutes at

    I took an action, which I’ve initiated – still awaiting the correct citation, but the mapping of diffuse white to 75% in HLG is defined in the ITU HDR operational practices document.

    Fredrik, BBC has some feedback for you on the document you shared, it’d be good to get in touch about this as soon as possible – maybe in the next couple of days if you’re still at TPAC?


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