Hello all,
I compared colours of the overprints specified by ISO 12647-2:2004 (WB) and
the Lab values I read on 100/100 samples which I had transferred from CMYK
to Lab using abs col method and ACE in Photoshop CS and ISOCoated.icc
profile. There were quite high DEs.
C+M DE=10, M+Y DE=7.3, C+Y DE=5.2
May be this method of acquiring Lab values isn't too correct. Regardless the
results surprised me, and I don't think it's only due to the way I got the
numbers. An old Matchprint laminate proof I examined (using same method, I
have its ICC profile) conforms to the values specified in the standard
better than ISOCoated.icc profile :-(
When I compare the samples using DEcmc, the results are more acceptable. But
there are questions: is it OK if colour differences (DE, not cmc) are so
high in this profile? Why this? Why data which, I think, couldn't too
conform to the standard were used? Will be there more accurate generic
profile with such a support as ISOCoated.icc has got?
I'm novice in this field. (In writing in English too, I am sorry.) Please
excuse me whether what I wrote is nonsense. But I want to know, where the
truth is. I though the today best practise is using ISOCoated.icc. However,
if the colour differences are so high, it would be better to use another
profile. Wouldn't be?
Regards, Petr
Petr Lozan, Student - Higher Graphic School Prague, Czech Republic
petr.lozan(a)volny.cz
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