color calibration and xvideo (xv)

[Alex Deucher]

On 8/21/07, Friedrich Schiller <freddy_schiller at yahoo.de> wrote:
> Hello,
>
>     I am wondering whether there is a way to configure the X11 system
> to have the xvideo (xv) interface respect color calibration?
> Specifically, xv seems to ignore the "color lookup table" (LUT)
> provided by the graphics hardware.
>
> Typically, on startup of gdm I call "dispwin" or "xcalib" to load
> a suitable color profile (from a icc / vcgt / cal file) into the video card LUT.
> On my system this greatly enhances colors and removes the strong
> color cast of my monitor (I used argyll for profiling).
>
> However, I have noticed that programs using the xv interface apparently
> do not make use of the LUT, hence they do not benefit from color calibration at all.
> As a result, for instance when I open a video, say, in VLC there is
>
> absolutely no color correction of the movie itself - even though the surrounding
> Gnome desktop is color corrected.
>
> I find this a bit puzzling as I thought the color correction is done by the
> hardware (via the LUT)?
>
> Is there any way to fix this?  Currently, my solution is simply not to
> use xv but instead force the video player to use the standard X11 interface...
>
> Many thanks for any hints.  I'd be also grateful for pointers to the correct forum
> or mailing list is this one is not appropriate.

On most hardware the LUT only handles the graphics plane.  The overlay
plane usually has it's own controls.  The are most often exposed as Xv
attributes.  Use an app like xvattr to adjust them.

Alex