[FFmpeg-user] [Cin] FranceBB's LUT collection

[Erik Dobberkau]

>
>>> BT2020_HDR_PQ_to_BT709.cube - this CLUT doesn't exist. That's Ultra
>>> Blu-ray HDR input to Blu-ray SDR
>>> output -- two colorspaces that are as common as dirt -- but such a CLUT
>>> doesn't exist!
>>>
>>> BT2020_HDR_PQ_to_<something>.cube followed by <something>_to_BT709.cube
>>> --
>>> <something> being an
>>> intermediate colorspace in common -- but such a <something> doesn't
>>> exist.
>>> I tried every combination
>>> that makes any sense and a few that make no sense.
>>>
>>
>> IIRC you need tonemap related filter for HDR to SDR conversion.
>>
>> Simple LUT can not do it.
>>
>
> The CinGG CLUTs do everything in one step, so, no, IIRC you don't need to
> tonemap because they tonemap. They take input yuv pixels from the input
> colorspace and output yuv pixels in the output colorspace.
>
>
IIRC, the missing piece to map from 2084 PQ to SDR may be that you need to
know are the maxFALL and maxCLL values to have a frame of reference (your
virtual 1.0 clipping point), because the content has rarely been color
graded for the theoretical 10,000nt display...