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U.S. Web Coated (SWOP)v2 vs. SWOP2006_Coated5v2
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U.S. Web Coated (SWOP)v2 vs. SWOP2006_Coated5v2


  • Subject: U.S. Web Coated (SWOP)v2 vs. SWOP2006_Coated5v2
  • From: Todd Shirley <email@hidden>
  • Date: Fri, 4 Jan 2008 19:11:23 -0500

This is more a "topic for discussion" than an actual problem, but it does effect my work and it IS driving me a little crazy, so I'd really like to hear from the colorsync list!

As most of you know, the default CMYK profile in the color settings of photoshop is U.S. Web Coated (SWOP)v2.icc. The profile on my machine is from 2000 and this has been the default as far back as I can remember. This is based on web printing on a #5 coated stock. As most of you also know, there is a much newer profile for web printing on a #5 stock called SWOP2006_Coated5v2.icc which is freely available at gracol.org. Would anybody like to expound on the differences between these 2 profiles? I'd love to hear it!

I know that the new profile is based on averaged (massaged) data from a number of presses calibrated using G7 methodology and that the old one is based on presses set-up to the old SWOP TVI/density numbers, but that's about all I know. Where did Adobe get the old SWOP profile? Did anybody ever use it outside of photoshop? Does anybody know the "story" of that particular profile? On other lists there have been long debates (arguments) about how it turns certain blues purple and its many other shortcomings, but it must have had some validity to become the photoshop default... right? There are a number of differences I can spot easily in Colorthink, not the least of which is that the new profile is about 5x larger (2.6mb vs 550kb) and that it's gamut volume is about 4% larger, but there is some interesting/ troubling behavior in photoshop that I'm hoping someone can shed some light on.

Let's say (hypothetically) that I have an untagged CMYK image that I have no idea where it came from or what profile (it any) was used to make it, and I have no way of finding out, and yet I'd like to convert it to RGB to do some color work and then further convert it to a known good CMYK profile (such as SWOP2006_Coated3v2.icc) to proof and release. In the past when faced with this I generally had pretty good luck assigning the photoshop default (U.S. Web Coated (SWOP)v2) and then converting to my RGB working space. Today I was testing this workflow by assigning different CMYK profiles to my mystery CMYK image and looking at the resulting Lab values to see what was "going on", and that's when I really started to wonder about the differences between U.S. Web Coated (SWOP)v2 and SWOP2006_Coated5v2.

Through most of the image there is not too much difference between the two, with the new one being about 2-3 points higher on the L axis. But when I get into the deep shadow, where image detail disappears into black, the old profile causes the image to plug up at a much lighter point and more "sharply". Here are a couple CMYK values and the resultant LABs so you can see what I mean. (Of course you can easily test this yourself).

C, M, Y, K     new SWOP Lab     old SWOP Lab
46,51,59,82      17,4,5                 14,4,7
58,57,63,90      10,3,3                   5,2,4
68,63,62,94	  6,2,1                   1,1,2

FYI, this image has a max ink limit of about 290%. The first value is somewhat typical of the bulk of the image, and the other 2 show how assigning the new profile leaves the deep shadows more open, with detail visible right up to the ink limit, while assigning the old value plugs up the detail at about 280%. This might seem minor, but it can have a huge effect on dark images, and I am just very curious why it does this. Did old SWOP presses plug up much easier than they do now? Is this just another example of how the old profile is "broken"? In ColorThink I can see that the A2B LUTs are about 13x bigger in the new profile - is there just not enough data in the LUTs of the old profile?

Well, I could go on, but this is already a monster post so I'll leave it at that. Thanks in advance for your comments!

–––
Todd Shirley
Urban Studio
New York, NY



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  • Follow-Ups:
    • Re: U.S. Web Coated (SWOP)v2 vs. SWOP2006_Coated5v2
      • From: Roger Breton <email@hidden>
    • Re: U.S. Web Coated (SWOP)v2 vs. SWOP2006_Coated5v2
      • From: Terence Wyse <email@hidden>
References: 
 >RE: Colorsync-users Digest, Vol 5, Issue 4 (From: "Mark Rice" <email@hidden>)

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