[argyllcms] Re: Gamut mapping problems in 1.1.0
- From: Idea Digital Imaging <qcore@xxxxxxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Mon, 9 Nov 2009 15:14:59 +0000
On 9 Nov 2009, at 04:28, Graeme Gill wrote:
qcore@xxxxxxxxxxxxxxxx wrote:
The gamut mapping appeared to me to be working in that the
separations themselves were as I expect (and love) from using
Argyll -- smooth, detailed, minimised clipping etc -- but mapping
to an oddly restricted version of the ISO Coated v2 gamut.
I need a specific example to track this down, as I haven't seen
anything like this in my testing.
That's probably because you've adjusted it so that it works exactly
as it should do whereas I'd like it to work in a way that'd suit the
tastes of London fashion photographers and retouchers :-)
I've grabbed part of the Bill Atkinson Lab Test image and converted
it to Adobe RGB (1998):
<http://inside.rgb2cmyk.com/images/ChartTest_aRGB.tif>
Made a device link using gamut mapping in both 1.0.4 and 1.1 using
collink -v -ip -G -cmt -dpp AdobeRGB1998.icc ISOcoated_v2_eci.icc
I converted the image using cctiff and then masked the results so
that you can see the 1.0.4 version on the left and 1.1 on the right
as strips:
<http://inside.rgb2cmyk.com/images/104-110aRGB-ISOc.tif>
Note that 255 255 255 --> 0 0 0 1.38 in the 1.0.4 conversion.
With real images the results when proofed/printed (I ran some FOGRA
proofs just now) are subtle, but saturated originals like the sunset
and the tree above it (on Bill Atkinson's test page) lose the visual
impact that the non-gamut mapped versions have and that the 1.0.4
version does a good job at preserving:
<http://inside.rgb2cmyk.com/images/SunsetTest_110.tif>
<http://inside.rgb2cmyk.com/images/SunsetTest_104.tif>
<http://inside.rgb2cmyk.com/images/TreeTest-110.tif>
<http://inside.rgb2cmyk.com/images/TreeTest-104.tif>
(I bet Klaus prefers the 1.1 red leaves but I think they are a little
dull...)
More delicate images like the rose on the test image also lose out as
the "glow" of the petals is reduced by the 1.1 gamut mapping.
I tried both -ims and -is intents in 1.1 but still couldn't get the
separations to match the saturated colours I'd been getting in 1.0.4.
--
Martin Orpen
Idea Digital Imaging Ltd
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