[ECI-EN] Re: ECI-EN digest, Vol 1 #96 - 5 msgs

Send ECI-EN mailing list submissions to eci-en(a)lists.transmedia.de To subscribe or unsubscribe via the World Wide Web, visit http://lists.transmedia.de/mailman/listinfo/eci-en or, via email, send a message with subject or body 'help' to eci-en-request(a)lists.transmedia.de You can reach the person managing the list at eci-en-admin(a)lists.transmedia.de When replying, please edit your Subject line so it is more specific than "Re: Contents of ECI-EN digest..." Today's Topics: 1. Re: RGB to CMYK with ISO web coated profile (Andy Psarianos) 2. Re: RGB to CMYK with ISO web coated profile (Chris Murphy) 3. Re: RGB to CMYK with ISO web coated profile (Peter Kleinheider) 4. Re: RGB to CMYK with ISO web coated profile (Paul Sherfield) 5. Re: RGB to CMYK with ISO web coated profile (Peter Kleinheider) --__--__-- Message: 1 From: Andy Psarianos <andy(a)psarianos.com> Subject: Re: [ECI-EN] RGB to CMYK with ISO web coated profile Date: Tue, 3 Aug 2004 21:46:12 +0100 To: eci-en(a)lists.transmedia.de Reply-To: eci-en(a)lists.transmedia.de Paul, Thanks that's really helpful. Yes indeed I am talking about the latest release of the profile called "ISO web coated" For example if I convert the following values I get the following results. From RGB Adobe 1998: RGB 50,50,50 to "SWOP" CMYK = 70,64,63,62 (C highest and M and Y are similar values) RGB 50,50,50 to "ISO web coated" CMYK = 64,53,48,71 (C highest M in middle and Y lowest) I'm not saying SWOP is correct, but if I were to remove the black separation it would appear grey wouldn't it? I don't believe the values in the ISO web coated values would be neutral. If this is the case, the question is why? I do understand that the lack of yellow in the dark greys could be hidden by the heavy black, but I don't understand why this was done, and why a more "conventional & balanced grey" was not chosen. Is it simply that when printing shadows with equal amounts of m and y they have a "yellowish hue" or is this an ink trapping issue? Overall, all tests I've done with the ISO web coated profile in conversions results have been very good. I'm willing to accept that these "unconventional values" in principle are OK, although I have several sceptics here which I need to convince. I would like to know what the reason was for this choice, if indeed it was a choice. Can anyone help shine some light on this decision? many thanks Andy Psarianos On 30 Jul 2004, at 18:38, Paul Sherfield wrote: ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ --__--__-- Message: 2 Cc: Andy Psarianos <andy(a)psarianos.com> From: Chris Murphy <lists(a)colorremedies.com> Subject: Re: [ECI-EN] RGB to CMYK with ISO web coated profile Date: Tue, 3 Aug 2004 15:03:16 -0600 To: eci-en(a)lists.transmedia.de Reply-To: eci-en(a)lists.transmedia.de On Aug 3, 2004, at 2:46 PM, Andy Psarianos wrote: I see this frequently with inkjet printing. If the yellow ink is very saturated (pure) compared to the other inks, it will take less yellow to balance the blue produced by cyan and magenta. And some yellow inks can be fairly green, which would take more magenta to further offset that contamination in the yellow. Off hand I can't say what yellow ink hue is being used with ISO web coated, but this is probably what's going on. This is why color by the numbers doesn't work unless you know the inkset and the print behavior of the press/printer very well. CMYK numbers are ambiguous. Chris Murphy Color Remedies (TM) www.colorremedies.com/realworldcolor --------------------------------------------------------- Co-author "Real World Color Management" Published by PeachPit Press (ISBN 0-201-77340-6) --__--__-- Message: 3 Date: Wed, 04 Aug 2004 10:49:03 +0200 From: Peter Kleinheider <pkleinheider(a)a1.net> Subject: Re: [ECI-EN] RGB to CMYK with ISO web coated profile To: eci-en(a)lists.transmedia.de <282E5EE1-E58E-11D8-A683-000393468A5E(a)psarianos.com> Reply-To: eci-en(a)lists.transmedia.de Andy When you do a relativ Colormetric Conversion from AdobeRGB to ISO Web Coated, a different way of gray-generation gets used as of perceptual. Since in a print run the yellow color is (usually) the last coler, Heidelberg (Profiles are done with Heidelberg PrintOpen) found that the yellow color is often reflecting and the color gets lighter the more yellow is on the sheet in a darkgray area. Therefor in the RelCol RI, the yellow color gets reduced a little bit more. Even at about 85% Gray, the values of yellow stall or drop when the color gets darker. When you separate using the Perceptive RI, you will find CMYK-Values that you would more consider as to be gray. But in real world pint production, you will not see much difference. Maybe Mr. Bestmann from Heidelberg cann explain that better. rgds Peter Kleinheider Am 03.08.2004 um 22:46 schrieb Andy Psarianos: --__--__-- Message: 4 Date: Wed, 04 Aug 2004 09:55:26 +0100 Subject: Re: [ECI-EN] RGB to CMYK with ISO web coated profile From: Paul Sherfield <paul(a)missinghorsecons.co.uk> To: <eci-en(a)lists.transmedia.de> CC: Andy Psarianos <andy(a)psarianos.com> Reply-To: eci-en(a)lists.transmedia.de Hi Andy It does look odd, but as Chris Murphy said the yellow can do strange things within a CMYK grey balance. I believe this GCR setting within the profile is causing the results you are seeing, reducing the yellow in a RGB to CMYK conversion to reduce the possibility of a yellow bias. The grey balance for ISO for the CMY is: Cyan Magenta Yellow Quarter tone 25% 19% 19% Mid tone 50% 40% 40% Three qu. tone 75% 46% 46% But this will not reflect the profile and any GCR that would be applied with a RGB to CMYK conversion. As you say the ISO profiles do work well, if the printers follow the standard printing conditions associated with each profile. Regards Paul The Missing Horse Consultancy Ltd Telephone: 01442 871752 Mobile: 07899 906385 --__--__-- Message: 5 Date: Wed, 04 Aug 2004 11:04:13 +0200 From: Peter Kleinheider <pkleinheider(a)a1.net> Subject: Re: [ECI-EN] RGB to CMYK with ISO web coated profile To: eci-en(a)lists.transmedia.de Reply-To: eci-en(a)lists.transmedia.de Paul This is just a recomendation and does not take in concern any color cast of the paper. the issue is: if a printer is printing according to ISO 12647, then the colors will turn out to be gray on the prints (when doing a separation of AdobeRGB or ECI-RGB to ISO Web coated) Am 04.08.2004 um 10:55 schrieb Paul Sherfield: Peter --__--__-- _______________________________________________ ECI-EN mailing list ECI-EN(a)lists.transmedia.de http://lists.transmedia.de/mailman/listinfo/eci-en End of ECI-EN Digest_______________________________________________ ECI-EN mailing list ECI-EN(a)lists.transmedia.de http://lists.transmedia.de/mailman/listinfo/eci-en