[argyllcms] Re: Gamut mapping problems in 1.1.0
- From: Klaus Karcher <lists@xxxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 09 Nov 2009 00:46:23 +0100
Hi Martin,
you wrote:
I'm using Argyll_V1.1.0_RC1_osx10.4_i86 and the gamut mapping isn't
working properly for me when building RGB to CMYK device link profiles.
Everything works as expected until either -g or -G are used. The results
are not any better when using source image gamuts either.
There is a loss of saturation immediately noticeable throughout the
resulting images.
Images which are highly saturated -- the seaside sunset image in Bill
Atkinson's Lab Target for instance -- will not give an acceptable result
if any type of gamut mapping is used.
How did you use tiffgamut and collink -g / -G on Bill Atkinson's Lab
images? Did you convert them to RGB? How? Which RGB? Did you cut-out the
individual images before using tiffgamut? (this will make a big
difference!) Did you try tiffgamut -f?
I'm still testing the new gamut mapping but I think there are some great
improvements compared to previous versions. You are right: there is less
saturation than in 1.0.3 or 1.0.4, but there are also much more details
preserved in saturated areas (e.g. in my red flowers example). While my
attempts to improve the gamut mapping parameters in GaMapICC 0.3b caused
overdone brightening in some saturated colors, there seems to happen the
opposite in 1.1.0 RC1 (e.g. with roman16_red and ISO coated v2).
Maybe this issue is related with a separation bug I noticed in
conjunction with collink's -ke flag: I generally get much more black
(and less CMY) than expected when I use collink -ke. There is e.g. no
cyan at all in skin tones, not even in the shadows, where I'd expect
20-30% cyan with a normal ISO Coated v2 separation.
I guess Graeme is on the way to Albquerque [I envy him!], so I think we
have to wait at least one week before he can see about this issue.
Klaus
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