Re: Enabling colour management in openGL code

[Aravindh M <aravindh 2138 gmail com>]

On Fri, Dec 24, 2010 at 4:28 PM, Richard Hughes <hughsient gmail com> wrote:
> On 24 December 2010 07:27, Aravindh M <aravindh 2138 gmail com> wrote:
>> I hope this does not apply the videoLUT part twice (once during
>> transformation and then by X).
>
> X doesn't actually do any color transforms. The only thing that is
> sent to the display is the VCGT to the gamma ramps of the output, but
> other than that, you can assume X will map 255 to 255 if you know what
> I mean.
>
> Richard.
>
Which part of Linux + gnome uses videoLUT to correct for white point
and gamma? Something should do 255 -> 1 and then 1 -> [1 ^ (1/x)], so
that finally gamma is 2.5. I just want to prevent 1 -> [1^(1/x)] ->
[1^(1/(x*x))] (applying the correction twice).
So will the following work:-
I use lcms2 to make a cmsHTRANSFORM htransform, using the profile
generated by gnome colour manager and a virtual sRGB profile (I guess
the transform is from the monitor profile to the sRGB profile). I need
to render different shades of red and green. Before rendering I
transform the colour (say 136, 0, 0) using htransform and use glColor
with the transformed values.

Thanking you,
M. Aravindh