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

[FFmpeg]

#10041: Problem with exposure filter
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             Reporter:  Michael Koch  |                    Owner:  (none)
                 Type:  defect        |                   Status:  closed
             Priority:  normal        |                Component:  avfilter
              Version:  git-master    |               Resolution:  invalid
             Keywords:                |               Blocked By:
             Blocking:                |  Reproduced by developer:  0
Analyzed by developer:  0             |
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Comment (by Michael Koch):

 Replying to [comment:6 Elon Musk]:
 > The invert of pixels bug have been fixed.

 The subtraction of s->black (now in line 70) doesn't make any sense in my
 opinion.
 And it would be better if the unit of "exposure" is photographic EV
 values, I mean exposure=1 should be a factor of 2 and exposure=-1 should
 be a factor of 0.5.

 I suggest to replace lines 70-73 by

 s->scale = exp(s->exposure * log(2.0))

 It's always positive.
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Ticket URL: <https://trac.ffmpeg.org/ticket/10041#comment:7>
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