[argyllcms] Re: Display profiling problem

  • From: Graeme Gill <graeme@xxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 29 Mar 2012 00:00:00 +1100

George Pop wrote:
> I finally managed to create a profile that solves my black crush problem. The 
> solution was to
> select the "gamma + matrix" type. Could someone please explain why I had 
> success with this, but not
> with shaper/matrix or LUT + gamut mapping?

        seems like coincicence. Without some detective work it's not really
possible to do more than speculate and twiddle knobs.

By detective work I mean carefully evaluating the displays behaviour
near black, and then doing similar tests on various aspects of
the workflow (ie. how the applications, CMM and profiles affect the
near black behaviour).

> Does using a gamma + matrix profile make the "perceptual" option in color 
> managed apps meaningless?

Yes. Matrix profiles can't have gamut mapping.

> Is the fact that matrix-based profiles cannot have the Perceptual intent a 
> limitation of Argyll?

It's a limitation of the ICC profile format.

> Inspecting with iccdump some profiles created with other software, they look 
> more like matrix
> profiles (no A2B tables), and yet in the header they indicate Perceptual as 
> the rendering intent.

The header is lying. The ICC spec. says that matrix profiles can only be 

Graeme Gill.

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