3 Replies Latest reply on Aug 5, 2008 2:55 PM by (Mike_Ornellas)

    New ICC standard?

    shoot me now-d3u3se Level 1
      So while stumbling around the Internet this morning in a caffeine-deprived stupor, I found some talk about a new gamma curve for an upcoming revision of color management policies. It read, in part:

      To complicate the matters, L* curve will become an official recommendation for ECI RGB V2...To complicate the matters yet further, 1976 CIE L*a*b* colorspace is not perceptually uniform in areas of high chromaticity, and also the original 1976 L* curve was ill-defined mathematically (it had noncontinuity in shadow areas leading to problems in matrix inversions). This lead to the replacement of traditional CIE L*a*b* delta-E used in evaluation of profiles with CIE DE-2000.

      The upshot of all this is, I followed links to these two pages:

      http://www.swop.org/

      http://www.colormanagement.org/en/swopprofile.html

      Of particular interest to me are the SWOP profiles in the second link. Are they of any value or should I avoid them like the plague? Your opinions and comments are welcome. :)

      EDIT: oh yeah, a new Lab profile was thrown into the mix as well...

      http://www.brucelindbloom.com/UPLab.html
        • 1. Re: New ICC standard?
          Level 1
          In case you are interested to learn more about the how's and why's of the eciRGB v2 profile (beyond the documentation that can be found on www.eci.org, section "Working colour spaces") I suggest to pay the [ECI-EN] mailing list a visit: that's the mailing list of the European Color Initiative, who developed and published the eciRGB profiles, and all the experts are around and will happily share their take. For subscribing go to the "Mailing lists" section on the ECI web site (www.eci.org).

          HTH.

          Olaf Drümmer
          Chairman of the European Color Initiative
          • 2. Re: New ICC standard?
            Correct me if I am wrong, but I believe that the L* gamma curve is only for monitor calibration and has nothing to do with delta-E calculations in CIE L*a*b*. It also has nothing to do with the new SWOP data sets that your links refer to. The profiles you link to are high GCR profiles made from the same data as the "official" profiles available through IDEAlliance: http://www.idealliance.org/swop/resources/

            Both the IDEAlliance and colormanagement.org profiles are perfectly valid if you are printing to those conditions. The data sets describe averaged web-offset print conditions on #3 and #5 coated sheets respectively, and can be used without fear! There is also the GRACoL_Coated1 data set and profiles, which describes sheetfed printing on a #1 coated sheet, which may also be appropriate, depending on how you are printing.

            I don't know much about Bruce Lindbloom's "Universal Perceptual Lab" profile, but once again, I don't think this has any bearing on SWOP datasets or profiles.

            -Todd Shirley
            • 3. Re: New ICC standard?
              Level 1
              L* will be finally fixed! About time...