[argyllcms] Weighted averaged source gamuts

  • From: "H. Teeuwen" <teeuwen@xxxxxxxxx>
  • To: <argyllcms@xxxxxxxxxxxxx>
  • Date: Tue, 24 Jul 2007 00:10:07 +0200

Hi,

I have been playing around with a new online profiling service called
'Online Profiler' (http://colorxact.selfip.com).

I found it very interesting that the underlying software can handle 3
different presets for gamut mapping, a quote from their forum:
---Start quote---
"In our Online Profiler you can find three different presets for the gamut
mapping.
They represent the source gamuts.

1. Default:
Weighted averaging of sRGB, AppleRGB, and GenericRGB (Apple) with a sRGB TRC

2. Enhanced:
Weighted averaging of AdobeRGB and ECI RGB v2 with a L* TRC

3. Big:
Pro Photo RGB with a L* TRC

But this 3 presets are only the half way to our perceptual rendering.
Not less important is the possibility to use the CIECAM02 appearance model,
which can be found under "viewing conditions"."
---End quote---

I have just started experimenting with Argyll cms and I'm know redoing some
profiles that I initially created with Profilemaker.
As Argyll cms allows to specify an icc profile to apply gamut mapping to
perceptual and saturation B2A table, I was wondering how to go about when
creating an weighted averaged matrix profile myself.

Three questions:

- Supposed that I'm able to create/tweak such profiles myself, could I just
average the white point and primaries of two working spaces (as specified in
profile which is always relative to D50) and include and sRGB or L* tone
response curve?
- How do I average white point and primaries?
- For the weight, could I use something like the relative occurrence of each
of the working spaces? For example, suppose that 75% of images that will be
used with a specific profile is in sRGB, and 25% is in aRGB, and then use
these percentages for the weight?

Thanks in advance for any help,

Herman



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