Re: basICColor_Testimages_2007
Re: basICColor_Testimages_2007
- Subject: Re: basICColor_Testimages_2007
- From: Jan-Peter Homann <email@hidden>
- Date: Thu, 22 May 2008 09:37:54 +0200
Hello Roger,
www.colormanagement.org is hosted by basiccolor and not by Jan-Peter (me).
The differences in you are noticing in the gamut warning are connected
to the tables of the perceptual intent.
Quite interesting to compare are also the tables CMYK->perc->Lab of
profiles based on the same characterization-data.
This can be done e.g. with the colorsync utility or ColorThink.
The CMYK->perc->Lab expansion is the inversion of the Lab->perc->Lab
compression.
If You compare this, you understand why current profilers are showing
differences up to Delta E 25 for the perceptual compression of some
color areas of e.g. Adobe RGB or the perceptual reference medium gamut.
Regards
Jan-Peter
Roger Breton wrote:
Just want to express my gratitude to basICcolor for having put together and
freely offering the above suite of color images for testing various aspects
of output profiles.
For those interested, the images are here, at the bottom of the web page :
http://www.colormanagement.org/en/download.html
Thank's Jan-Peter for hosting the files, btw.
I find particularely interesting how different profilers can seemingly
expand and contract the gamut of the same printing press when converting
from Lab. I use SWOP2006_C3 profiles from Monaco, Kodak, PrintOpen,
ProfileMakerPro, TGLC and basICcolor (will study ColorProfilerSuite from
Fuji later).
I particularely like the "TestingSeparations_ChannelAllocation-en.tif".
Selecting different output profiles in GamutWarning, in Photoshop, leads me
to believe that some profilers are able to extract more or less colors out
of the same dataset. To see this for yourself, try toggling GamutWarning in
the View menu and then activate ProofColors > Setup and select a different
SWOP2006 profile to study in the Device to Simulate menu, leaving the RI
constant (I like Perceptual).
My question is this: are the differences in gamut we're seeing real?
Roger Breton
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