Re: Rendering intents in source profiles?
Re: Rendering intents in source profiles?
- Subject: Re: Rendering intents in source profiles?
- From: Klaus Karcher <email@hidden>
- Date: Sat, 26 Jul 2008 14:36:13 +0200
Marc Levine wrote:
[...] In other words, A2B tables are supposed to be the inverse of
the B2A tables.
Am 25.07.2008 um 19:31 schrieb Klaus Karcher:
That's what the ICC whitpaper provideds. Unfortunately this symmetry
conflicts with the aim of the perceptual intent as Graeme pointed out.
Uli Zappe wrote:
Which of Graeme's points exactly do you refer to?
Graeme Gill wrote:
My guess has always been that the the allowance for intent in the
A2B tables is part of a (flawed or at least limited) scheme
to make gamut mapping work in the ICC profile world, by allowing
the input profile to map the input device gamut to a "standard"
PCS gamut, and then have the output profile map from the PCS gamut
to the output device gamut. It's limitation is that it only
really works for (what I would call) saturation intent, since
the gamut surfaces will be mapped to gamut surface (expansion
of gamut as well as compression).
There was a similar thread in February ("PRMG gamut"), here a very brief
summary:
Graeme Gill writes on Thu, 28 Feb 2008 13:49:10 +1100
The reference gamut is great if you like saturation rendering,
not much good if you want perceptual though.
(The implications of the ICC requirements that the
A2B table gamut mapping be the inverse of the B2A
gamut mapping imply that the mapping be a saturation one.)
Here is Grames page with a more detailed explanation (part of the
ArgyllCMS doc):
<http://argyllcms.com/doc/iccgamutmapping.html>
Klaus Karcher wrote:
It took a while until I understood and accepted his sobering conclusion.
I tried to illustrate the pitfalls schematically in this PDF:
<http://digitalproof.info/colorsync-users/GamutMapping.pdf>
Klaus
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