[FFmpeg-user] overlaying a clut over a picture

[Michael Koch]

Am 14.01.2019 um 08:40 schrieb Michael Koch:
> Am 14.01.2019 um 07:28 schrieb Michael Koch:
>> When I create a color-look-up-table with this command line, the 
>> result is a 512x512 clut saved as 16-bit PNG. It works as expected 
>> and I checked that the top left pixel is black (R=0, G=0, B=0) and 
>> the bottom right pixel is white (R=65026, G=65026, B=65026).
>>
>> c:\ffmpeg\ffmpeg -f lavfi -i haldclutsrc=8 -frames 1 -pix_fmt rgb48be 
>> -y clut.png
>>
>>
>> In the next example I wanted to extract one frame from a video, 
>> overlay the clut in the top left corner, and save it as 16-bit PNG. I 
>> need 16-bit PNG because my video is 10-bit. At first glimpse the 
>> result looks good, but a closer examination finds that the top left 
>> pixel is not pure black, it's R=0, G=1285, B=0, and the bottom right 
>> pixel of the clut (at coordinates 511,511) is not pure white, it's 
>> R=65535, G=63736, B=65535. Why are the colors wrong?
>>
>> c:\ffmpeg\ffmpeg -ss 5 -i P1000099.mov -f lavfi -i haldclutsrc=8 
>> -filter_complex overlay -frames 1 -pix_fmt rgb48be -y 
>> Image_with_CLUT.png
>
> I found a solution myself:  overlay=format=rgb

But the output of the overlay filter seems to be RGB24. Is it possible 
to get RGB48 out of the overlay filter? Or is there any other filter for 
overlaying two RGB48 images?

Michael