[FFmpeg-user] How to brighten part of a dark video?
barsnick at gmx.net
Fri Sep 18 11:44:29 CEST 2015
On Fri, Sep 18, 2015 at 11:25:35 +0200, Gilles wrote:
> Can ffmpeg brighten up only the dark part of the video without
> increasing the brightness of the screen that's already too bright?
Sure. You can use a complex filter to crop one section out, apply
different brightness changes to the original and the cropped part, and
reoverlay to cropped part onto the original.
$ ffmpep -i vlcsnap_2015_09_18_11h21m29s599.png -filter_complex "split=2[v1][v2]; [v1]crop=200:300:520:0,mpblablabla[brightpart]; [v2]mpbablabla[darkpart]; [darkpart][brightpart]overlay=x=520:y=0[v]" -map "[v]" corrected.png
I don't know if the mp filter or on of the lut filters is best.
Whatever you use, insert it instead of "mpblablabla" above.
What that filter chain does: It duplicate the input. It uses [v2] as
the base, where you would increase the brightness or whatever. [v1]
crops out the very bright section, optionally decreasing its
brightness. It reassembles them by overlaying the corrected bright part
over the corrected base (at the same position as before, hopefully).
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