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Old 31st July 2020, 15:37   #37  |  Link
wswartzendruber
hlg-tools Maintainer
 
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Join Date: Feb 2008
Posts: 410
Hi there. Someone brought this thread to my attention after demo'ing some work I did on a HDR10 to HLG converter.

Quote:
Originally Posted by butterw2 View Post
Based on this sample (upconverted SDR most likely), my main takeaway is that the HLG backwards compatibility on SDR (HDTVs) is quite underwhelming.
I think the main issue you guys are running into is 2020 to 709 color mapping. HDTVs do 709. 4K TVs do 2020. Most 4K TVs are HDR, but some are SDR, particularly older ones. HLG was designed to be compatible with these 4K SDR TVs that still did 2020 color. HLG was never really intended to display properly on HDTVs.

Quote:
Originally Posted by butterw2 View Post
However some processing as performed in vlc might improve on this result.
VLC does indeed have excellent algorithms for mapping 2020 to 709. They're actually quite good. I've uploaded some screenshots of Alita: Battle Angel in HLG displayed by VLC.

Quote:
Originally Posted by butterw2 View Post
A purist however might say that HDR can only be properly displayed on a HDR screen.
HDR is a complete and total mess, if I may be frank. But HLG is much better about SDR as long as the HLG picture is balanced correctly, meaning that reference white is calibrated to 75% input signal strength. Again, a purist is going to say that HLG should always be shown on a 2020-capable device.
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