I found something rather unexpected when converting a colour from sRGB to CMYK using this new ISOCoated_v2_eci.icc in Photoshop CS2.
The below conversions were all done in Photoshop CS2 using Engine=Adobe(ACE) & Black point compensation on.
R=0 G=0 B=255
converted to:-
Intent = Relative Colorimetric, ISOCoated_v2_eci.icc C=95 M=100!! Y=0 K=0
Fogra27 C=88 M=77 Y=0 K=0
The ISO version is turning the blue, purple! Where as the Fogra27 is strikingly more blue.
Since when have we made blue from more magenta than cyan?
Strangely, when I converted pictures, using the same profile and intent, I've generally seen more black generation with the ISOCoated_v2, with much less magenta and yellow being added than with the previous Fogra27 profile.
And for comparison the following differences show up when changing the intent.
Intent = Perceptual
ISOCoated_v2_eci C=96 M=81 Y=1 K=0
Forga27 C=90 M=79 Y=0 K=0
So with the Perceptual Intent the ISOCoated_v2_eci magenta content is less than Cyan creating a blue, slightly 'bluer' than even the Fogra27.
Intent = Absolute Colorimetric
ISOCoated_v2_eci C=87 M=100 Y=0 K=0
Fogra27 C=89 M=78 Y=0 K=0
But with the Absolute Colorimetric Intent the ISOCoated_v2_eci magenta content is more than Cyan creating a purple.
The Fogra27 profile does seem to be much more stable in creating a blue from a blue! All the conversions using Fogra27 have resulted in more cyan being generated than magenta leading to blues not purples.
Is this a bug in the new ISO profile!? Even if it's not a bug, I think it's rather concerning and is enough for me to put plans for changing over to using the ISO profile on hold until I've got more information and done more testing. (By the way, the same type of results are also encountered when using the uncoated and 300 versions of the ISO profiles)
Matthew
On 21 Feb 2007, at 00:44, Russ Wyatt wrote:
Hi List,
Does anyone know if Adobe will be creating a new ISO Coated V2 - FORGA 39L Photoshop icc profile replacing the EuropeISOCoatedFOGRA27.icc profile?
Regards,
I'm hoping they don't, and use the ISO Coated v2 (ECI) one. There are too many choices available, and without guidance, many Photoshop users make the wrong choice. Also, what's the point of having 2 profiles that describe the same thing? I can see why specialist CMYK generation may be necessary in some cases, but we should all use the same ICC profile for general CMYK generation. The reason not to use the same one can only be a legal/licensing one. The dataset is freely available (I think), but the ECI profile is copyright ECI.
Russ Wyatt Colour Manager
Group Momentum www.groupmomentum.com.au
Lee Badham Bodoni Systems Ltd www.bodoni.co.uk
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