Bob Marchant wrote: Not only eci profiles produce anormalies, not only in saturated blues and not only in one intent ;-) ... but an image says more than thousand words: take a look at this one (it's a Lab TIF, so you have to download it and view it with Photoshop): http://digitalproof.info/perceptual-rendering/gelb-vgl.tif Regards, Klaus

Klaus Karcher wrote: Thats not surprising. The LAB-Values of the original are 99/-10/47, for example. This color is far far out of gamut of CMYK and out of gamut of (ECI-)RGB. IMHO that is not a real but a virtual color. Kind regards, Jörg Schober

Klaus Karcher wrote: Klaus Karcher wrote: I have to revise this statment: it must be a real color (by definition): Adobe RGB has real primaries and you can not mix virtual colors with real primaries. Klaus

Guys, I have tried to reproduce this blue/purple problem a few times now and have been unable to reproduce ! ? Am I missing something here? I know Bob has brought this up more than once, so it obviously happens. Does someone have an example, as I am now quite puzzled by this reported deficiency? -Andy Psarianos F E Burman Limited On 9 Nov 2005, at 20:32, Chris Murphy wrote:

OK Bob, I see clearly what you're alking about now, although that is a pretty wacky colour... I know the stuff you shoot may very well have these kinds of colours in them, although my intuition would be to stay away from the colorimetric intents when using these "far out of gamut" colours. Actually I would probably reduce the gamut with all kinds of trickery in photoshop and then attempt to convert.. (I expect this is what you're doing anyway) None the less, you are right, this particular colour is rendered poorly in the ECI profiles when using colorimetric intents, BUT if you take the test one step further and instead of creating a fill of the colour create a gradient fill to white, you will see that the gradient remains somewhat smooth with the ECI profiles, and differs between perceptual and colorimetric in Hue only. More what I would expect. The Adobe profiles however do not have the same "smoothness" and introduce visible bands of shifting hues in the gradients... not so desirable in many cases. Neither is perfect, and it's a question of using the most appropriate for the content! -Andy Psarianos F E Burman Limited On 10 Nov 2005, at 16:25, Bob Marchant wrote:

Hi Bob and Andy and others I have been lurking all week re this subject, and find the discussion interesting and valuable. Bob seems to have a valid point re the ISO 'PrintOpen' produced profiles in the 'extreme' blues on the edge of the Adobe RGB gamut. But as most people are going to use the readily available CMYK profiles from Adobe and Fogra, I thought that as I had a little time today I would look at their 'performance' on a range of RGB images. I looked at 5 images, measuring their conversion from RGB to the 3 CMYK profiles in this thread. I looked at: Average Delta e 76 Max Delta e 76 % pixels in Gamut, allowing 3 Delta e as a tolerance The measurements use the Alwan ColorPursuit colour management workflow tool, and are for the Relative Colormetic intent. The Perceptual intent give slightly better figures, (but the CMYK profiles give the same relative performance,) but the colour appearance was not as good. Image 1 A very saturated modern art piece, shot on a Phase One camera back, Adobe RGB. Some of 'Bobs blues'. ISO coated /Europe ISO coated FORGA27 /Euroscale Coated v2 Average De 7.7 11.3 11.8 Max De 40.6 55.3 65.8 %Pixels in Gamut 39% 37% 36% Image 2 A food shot from a Fuji S2 in s-RGB ISO coated /Europe ISO coated FORGA27/ Euroscale Coated v2 Average De 2.1 2.7 2.9 Max De 19.6 29.0 27.0 %Pixels in Gamut 81% 79% 80% Image 3 A landscape shot with a large deep blue sky, scanned on a Nikon scanner into Apple RGB. ISO coated /Europe ISO coated FORGA27 / Euroscale Coated v2 Average De 14.0 15.9 15.9 Max De 23.0 25.9 35.1 %Pixels in Gamut 5% 5% 4% Image 4 Gold oriental statue, with a pastel background from a Leaf DCB, in Adobe RGB ISO coated/ Europe ISO coated FORGA27/ Euroscale Coated v2 Average De 4.5 6.0 5.9 Max De 23.0 31.2 29.7 %Pixels in Gamut 67% 66% 66% Image 5 A technical image in Lab with very saturated reds and 'Bob's blues' ISO coated/ Europe ISO coated FORGA27/ Euroscale Coated v2 Average De 11.2 13.0 12.4 Max De 72.7 81.0 80.0 %Pixels in Gamut 41% 39% 39% So it would seem that the ISO coated profile is, on this small sample, technically the most accurate of the 3 CMYK profiles. It would be interesting to compare Bobs ProfileMaker FOGRA 27 profiles to the above? The above findings were reflected in the appearance of the images, the ISO coated profile seemed the best visual match to the RGB images compared. No time to do more! Regards Paul Sherfield The Missing Horse Consultancy Ltd Telephone: 01442 871752 Mobile: 07899 906385 http://www.missinghorsecons.co.uk Apple Solutions Expert-Print & Publishing This email and any attachments may be confidential and are intended solely for the use of addressee. If you are not the intended recipient of this message, any disclosure, copying or other distribution is strictly prohibited and may be unlawful. If you have received this message in error, please notify the sender and delete all copies from your system. Email may be susceptible to data corruption, interception and unauthorised amendment. We do not accept liability for any such corruption, interception or amendment or the consequences thereof. We do not accept liability for any action or inaction by the recipient as a result of advice or information contained within this email.

Bob Marchant wrote: Is the visual match being made on a monitor or proof? Or Press :-) ? Hi Bob This was a visual 'softproof' match RGB to CMYK on a Sony LDC, calibrated and profiled with BasICColorDisplay 3.01. The monitor profile is about the same as sRGB and displays around 95% of ISO coated. The profile when validated by the BasICColor software has a average Delta e of .7 and a max of 2.4. I will run proofs on a clients GMG/Epson system over the next few days to compare the ISO/Fogra 27 profiles when used for the same RGB images. Are you going to the PPA production Conference? If so see you there? Regards Paul Sherfield The Missing Horse Consultancy Ltd Telephone: 01442 871752 Mobile: 07899 906385 http://www.missinghorsecons.co.uk Apple Solutions Expert-Print & Publishing This email and any attachments may be confidential and are intended solely for the use of addressee. If you are not the intended recipient of this message, any disclosure, copying or other distribution is strictly prohibited and may be unlawful. If you have received this message in error, please notify the sender and delete all copies from your system. Email may be susceptible to data corruption, interception and unauthorised amendment. We do not accept liability for any such corruption, interception or amendment or the consequences thereof. We do not accept liability for any action or inaction by the recipient as a result of advice or information contained within this email.