[FFmpeg-trac] #10041(avfilter:new): Problem with exposure filter

[FFmpeg]

#10041: Problem with exposure filter
-------------------------------------+-------------------------------------
             Reporter:  Michael      |                     Type:  defect
  Koch                               |
               Status:  new          |                 Priority:  normal
            Component:  avfilter     |                  Version:  git-
                                     |  master
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
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 Make a 10-bit grayscale test image:

 ffmpeg -f lavfi -i color=black:s=16x64,format=gray10le -lavfi
 geq=lum='X+16*Y',format=gray10le,datascope=s=640x768:mode=color2:format=hex
 -frames 1 -y test.png

 Apply the exposure filter, followed by a limiter:

 ffmpeg -i test.png -vf format=rgb48,exposure=exposure=1:black=0.4,limiter
 -y out.png

 exposure=1 should be equivalent to a factor 2, but the amplification in
 the output image is much stronger. It becomes even worse if black=0.5 is
 used, then the output image contains only black or white pixels, that's
 infinite amplification.
 Either something is wrong, or I did misunderstand what the filter is
 supposed to do.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10041>
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