[argyllcms] Re: convert shaper/matrix-based profile to vcgt/LUT-based profile? [restrict wide gamut display to sRGB]

  • From: "Marcus Blomenkamp" <mblomenk@xxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Mon, 15 Oct 2012 10:16:57 +0200

> Hi,
>       this is impossible using per channel cLUTs, since you need to
> move the chromaticities of the primaries, and that involves mapping
> a pure color to a combination of colors. This is why some wide gamut
> displays have an sRGB emulation mode.


the LCD does have an sRGB emulation mode but is still quite 'off' in the reds 
with a visible hint of pink, so this is not the final solution but maybe a 
starting point so the final corrections are less intrusive.

Assuming that the native primaries of the display combined with the primaries 
of sRGB form a near-zero vector product in CIE xy (same angle from white), 
would the per channel LUT still be wrong? Wrong in such a way that it could not 
be corrected/approximated by the appropriate combination of 
(brightness,contrast,gamma) as LUT ramp? 

> Your alternative is to do the mapping in your application. Note that
> while you can apply a source to destination transformation using
> CPU based CMM's (ie. Argyll's imdi, or lcms), you could also
> use OpenGL to apply a matrix profile or even a full 3D device
> link, using texture lookups.

I will have a look at it, but success stories seemed sparse when googling the  
respective terms. Before digging into that i will use the displays PiP 
side-by-side mode displaying profiled/managed content on one side and the 
non-managed LUT-calibrated content on the other side, trying to find the above 
mentioned sufficiently correct combination.


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