Re: [ECI-EN] Coated FOGRA39 vs. ISO Coated v2
4 Oct
2011
4 Oct
'11
10:25 a.m.
Claas, Vitor, Emmanuel,
sorry, Claas, it´s not just a matter of taste. The ISOcoated_v2_eci profile is faulty as
you can see when you convert (e.g.) the test image Test Out-of-Gamut colors.tif (1,2 MB)
from http://colormanagement.org/en/testimages.html to ISOcoated_v2_eci and to
ISOcoated_v2_bas.
There are JPEG artefacts in the image (headband, skin tones) which will be
"enhanced" with ISOcoated_v2_eci. The reason lies in "jagged" gamut
boundary in this profile (there are other flaws as well).
You can download (from www.basiccolor.de) and try "basICCoolTool profile´s
secret" to see the differences.
And no, the eci profile is not an official one and is not ISO! The basICColor profile was
made fromthe exact same characterization data from Fogra. And these are not ISO either!
ISO just specifies the printing condition – color values of the primary colors and dot
gains.
I do not want to diminish the achievements of the eci (being a member myself), I just want
to make clear that there are more ways than one and the user is free to choose the one he
likes best.
Best regards,
Karl Koch
Am 01.10.2011 um 12:55 schrieb Claas Bickeböller:
Dear Vitor,
what you see is the effect of different strategies for finding the best representative of
non printable colours (not reproducible colours are also called out-of-gamut colours).
As "the best" representative is highly ambiguous all vendors of profiling
solutions choose a strategy which they found to be the best.
You could also say that it's a matter of taste.
The process of finding printable representatives of not reproducible colours is called
gamut mapping.
If you are interested in the principles of colour gamut mapping I recommend the book
"Color Gamut Mapping" by Dr. Jan Morovic.
BTW: Make your test again but start using colours that are within the gamut of FOGRA39.
(You can make sure that they are inside e.g. by starting with FOGRA39 CMYKs and convert
absolute colorimetric to AdobeRGB.)
The remaining differences will be the separation strategy (black generation) as long as
you choose relative colorimetric for the conversion.
If you chose perceptual you are again facing ambiguous gamut mapping
"phenomenons".
Best regards
Claas
Am 30.09.2011 um 13:28 schrieb Vitor Pedro:
Good afternoon, I am a student of color
management in Portugal and would like to ask the following question:
- If the ISO Coated v2 Profile is based on FOGRA39, how can we explain the large
differences obtained in the conversion of primary and secondary colors from Adobe RGB, as
we can see in the PDF attachment that I did myself?
- In general, in the Adobe programs, the profile used to meet the standards is the Coated
FOGRA39 (ISO 12647-2:2004). It would be assumed that the ISO Coated v2 will produce the
same result, but it does not. Why? This is normal? It seems to me that the principles of
ICC Color Management are not working here, or am I to do some confusion or something
wrong?
Thanks for your help.
Vitor Pedro
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