[MEncoder-users] (automatic) white balance (eq2)

[Grozdan]

On Sun, Jun 27, 2010 at 5:03 PM, Al Bogner
<mencoder at ml093.pinguin.uni.cc> wrote:
> Am Sun, 27 Jun 2010 16:38:31 +0200
> schrieb Grozdan <neutrino8 at gmail.com>:
>
>> > Where can I find a description how eq2 works in detail, explaining
>> > the options?
>>
>> Read the man page
>
> Excuse me, but I searched a lot, before I asked this. There is a
> difference between reading and understanding.

You asked for description and explaining the options, which the man
page does. Also, seems your mplayer man page is a bit outdated. Here's
mine on it

Alternative software equalizer that uses lookup tables (very slow),
allowing gamma correction in addition to simple bright- ness and
contrast adjustment.  Note that it uses the same MMX optimized code as
-vf eq if all gamma values  are  1.0.   The
parameters are given as floating point values.
<0.1-10>
initial gamma value (default: 1.0)
<-2-2>
initial contrast, where negative values result in a negative image
(default: 1.0)
<-1-1>
initial brightness (default: 0.0)
<0-3>
initial saturation (default: 1.0)
<0.1-10>
gamma value for the red component (default: 1.0)
<0.1-10>
gamma value for the green component (default: 1.0)
<0.1-10>
gamma value for the blue component (default: 1.0)
<0-1>
The  weight  parameter can be used to reduce the effect of a high
gamma value on bright image areas, e.g. keep them
from getting overamplified and just plain white.  A value of 0.0 turns
the gamma correction all the way down  while
1.0 leaves it at its full strength (default: 1.0).



>
> mplayer -vf eq2=help
> Option vf: eq2 have no option description.
> MPlayer dev-SVN-r30099-4.4-openSUSE Linux 11.2 (x86_64)-Packman (C)
> 2000-2009 MPlayer Team
>
> http://tivo-mplayer.sourceforge.net/docs/mplayer-man.html
>
> eq2[=gamma:contrast:brightness:saturation:rg:gg:bg]
>
> Alternative software equalizer that uses lookup tables (very slow),
> allowing gamma correction in addition to simple brightness, contrast
> and saturation adjustment.
>
> Note that it uses the same MMX optimized
> code as -vop eq if all gamma values are 1.0! The parameters are given
> as floating point values.
>
> Defaults are gamma=1.0, contrast=1.0,
> brightness=0.0 and saturation=1.0. Parameters rg, gg, bg are the
> independent gamma values for the Red, Green and Blue components, all
> default to 1.0. The values are 0.1-10 for gammas, -2-2 for contrast
> (negative values result in negative image) -1-1 for brightness and 0-3
> for saturation.
>
>
> Sorry, I have no idea, how to _calculate_ values for the white balance.

By playing around/experimenting? I'm not very versed with this filter
myself, so I won't be of much help.

>
> Al
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