On Sun, 18 Sep 2005, E.Chalaron wrote:
> One of the movie that I got has its colours pretty washed out.
> I think Yuvcorrect would be the tool to boost a bit the chroma.
> However the few quick results that I have so show me that I have to (once
> again) RTFM a little bit more.
From the TFM (or rather 'yuvcorrect -h') we have:
CHROMINANCE_UVrotation_Ufactor_Urotcenter_Vfactor_Vrotcenter_UVmin_UVmax ...
to rotate rescaled UV chroma components Ufactor*(U-Urotcenter) and
Vfactor*(V-Vrotcenter) by (float) UVrotation degrees, recenter to the
normalize (128,128) center, and _clip_ the result to range [UVmin;UVmax]
> Can someone forward me a link OR (even better) tell me how it works.
You don't want to 'rotate' U or V since that will change the hue.
And unless you have a colorcast you probably won't be wanting to
change the center from the midpoint (128). That leaves only the
'Vfactor' (how much to increase/multiply) the values by.
So given all of that
yuvcorrect -Y CHROMINANCE_0.0_1.1_128_1.1_128_16_240
will do for 'U' a 'rotate' of 0.0 degrees, increase the values by 10%
(multiply by 1.1), leave the center point at 128 and for 'V' do the
same thing (0.0 1.1 128) and finally constrain both U and V to the
16 - 240 range.
Be conservative - I'd start with 1.1 (10%) and gradually move up from
there.
Now that wasn't so hard and bad - was it? ;)
Cheers,
Steven
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