[FFmpeg-user] Saturation adjustment only in some channels

[Martin Cracauer]

Stefano Sabatini wrote on Wed, Jan 01, 2014 at 01:21:07PM +0100: 
> On date Tuesday 2013-12-31 15:24:16 -0500, Martin Cracauer wrote:
> > 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?
> 
> colorbalance and colorchannelmixer filters may help.

Yes, that's what I'm using.  They don't allow you to mess with the
saturation in some channels only, though, and colorbalance's semantics
when it comes to how wide it considers "mids" are a bit unclear.

I noticed that the picture is blow out very quickly when using
colorbalance's mids, so it obviously does something that is different
from what e.g. GIMP considers mids.

Martin
-- 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Martin Cracauer <cracauer at cons.org>   http://www.cons.org/cracauer/