color calibration and xvideo (xv)
freddy_schiller at yahoo.de
Tue Aug 21 15:15:36 PDT 2007
Many thanks again!
> Is there something like that? If you pick the window with movie and move it
> around quickly, you should see the colorkey behind the movie (in the case of
> Radeon, it is usualy pink, the XV_COLORKEY says RGB value of the colorkey).
Yes, I do see the pink colorkey when I move the video lan client
very quickly. So I guess the LUT is indeed by-passed.
> the problem here could be that ICCM profile cannot be applied to XV overlays.
> You can basically change gamma/brightness/saturation and so on but you cannot
> apply the profile obtained somewhere somehow. And I guess this is probably the
> reason for the initial question.
Yes. Setting the three standard monitor parameters (Gamma, black
point, white point) allows only for very limited color correction.
In contrast, using the LUT provides a much more fine grained map between
internal color representation and actual color output.
As a matter of fact, I would have never believed myself that proper
color calibration makes such a difference, i.e. until I borrowed a friend's
colorimeter and used "argyll" to create a monitor profile.
The difference is really like day and night! For instance,
I always thought my digital camera has a tendency to produce "foggy"
picures - but in fact the colors are spot on and it was only a problem
of setting the proper color management in X11 ...
(see also http://en.wikipedia.org/wiki/Linux_color_management ).
And now when I watch a DVD (through color corrected X11) I almost
also can't believe how much richer and balanced the colors are ...
So it is good to see that there is awareness of this issue!
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