Ok - now I get it - thanks again.
Interesting software this argyll but not too user friendy for those not
customed to use command promts
Jouni
-----Original Message-----
From: eci-en-admin(a)lists.transmedia.de
[mailto:eci-en-admin@lists.transmedia.de] On Behalf Of Klaus Karcher
Sent: 7. marraskuuta 2005 11:24
To: eci-en(a)lists.transmedia.de
Subject: Re: [ECI-EN] Isocoated vs EuroscaleCoated vs.
EuropeIsocoatedFogra27
Hi Marttila,
you wrote:
Hello
Very interesting data - thank you. Yes I was using perceptual - with
relcol differencies are smaller and Isocoated/EuropeISocoatedFogra27
are much closer to each other than Euroscale.
However I don't fully understand your second picture - to
what do you
compare the Lab values to get Delta E94?
For the first picture I took a gray ramp in Lab (0/0/0 thru 100/0/0),
converted it to CMYK unsing the profiles and rendering intents
specified
in the legend and then converted it back to Lab using the absolute
colorimetric intent of the particular profile.
The data for the second picture comes from Graeme Gills "profckeck"
utility, documentation can be found at
http://argyllcms.com/doc/profcheck.html
As Test point data file I used FOGRA27
(
http://www.color.org/FOGRA27.html) converted to argylls ti3-Format.
Klaus
BR Jouni
>-----Original Message-----
>From: eci-en-admin(a)lists.transmedia.de
>[mailto:eci-en-admin@lists.transmedia.de] On Behalf Of Klaus Karcher
>Sent: 4. marraskuuta 2005 16:00
>To: eci-en(a)lists.transmedia.de
>Subject: Re: [ECI-EN] Isocoated vs EuroscaleCoated vs.
>EuropeIsocoatedFogra27
>
>
>Marttila Jouni wrote:
>
>>Hello
>>
>>I was just looking at some natural pictures with skintones etc..
>>
>>E.g. the picture attached where woman is drinking. By calculating
>>pixel by pixel the avg Delta E between
>>
>>ISOcoated and Euroscale = 4.36
>>ISOcoated and EuropeISocoatedFogra27 = 3.57
>
>EuropeISocoatedFogra27 and
>
>>Euroscale = 1.12
>>
>>So EuropeISOcoated is closer to Euroscale and main
>
>difference seems to
>
>>come from luminance level, which is higher with ISOcoated
>
>than the two
>
>>others.
>
>Are you talking about perceptual conversions from PCS to
Device unsing
>Adobe Euroscale Coated v2, Adobe
EuropeISocoatedFogra27, and
>eci ISOcoated?
>
>As I mentioned in January in the German list, the B2A0-Tables of
>PrintOpen Profiles (as used by the eci) induce this luminance
>displacement.
>
>see:
>http://digitalproof.info/perceptual-rendering/DeltaL.pdf
>
>* euCo2 means "Adobe Euroscale Coated v2"
>* isoC means ECI ISO Coated (PrintOpen)
>* IsoC-G3-350-CF is a ProfileMaker5 Profil
>
>and relTK means "relative colorimetric with blackpoint compensation"
>
>eci ISO Coated's perceptual rendering is significant lighter
than that
of most
other profiles and IMHO this shold be corrected in
further versions.
On the other Hand, both Adobe profiles (Euroscale Coated v2 and
EuropeISOcoatedFogra27) are imho not suitable for proofing
tasks (using
its colorimetric Tables), because the error produced already by the
profiles (not by the proofing system!) makes it realy
difficult to meet
the close tolerances for proofing, as you can see in
http://digitalproof.info/profcheck/profcheck5ir1b1.html
regards, Klaus
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