[FFmpeg-user] Saturation adjustment only in some channels

Martin Cracauer cracauer at cons.org
Tue Dec 31 21:24:16 CET 2013

I am doing color corrections on a video.  Used gimp to find the
correction adjustments.

I have two difficulties:

1) I need to apply saturation only to cyan (leave red alone). This
   isn't directly supported by the hue filter.

2) how do I clip a color? (the equivalent of using gimp color levels
   and moving left or right slider, or in color curves move one end of
   the curve on the x axis) I think it works reasonably fine but just
   pushing the highs of the color, can somebody confirm that.

In general, how do ffmpeg's colorbalance filter's ideas of low, mids
and highs translate to color curves? How much overlap do they have?

Anyway, problem #1 is far more important.  I need to really kill cyan
saturation and I verified that the outcome isn't good if I either kill
red, too, or if I replace red saturation with more red (captain
obvious has spoken).

I am willing to throw significant CPU power on this so if I have to
separate out the whole thing into red and rest, correct saturation and
blend them together afterwards I'd do that, too.

Or maybe I can specify a table that simply translates every possible
color value to a target value?

Thanks for your help.
Martin Cracauer <cracauer at cons.org>   http://www.cons.org/cracauer/

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