4 Replies Latest reply on Mar 14, 2008 7:36 AM by John Danek

    Trnasform Specifc RGB color to Specific CMYK color... How to?

      Hi to all!

      My question is this.

      I need to Transform a specific RBG (194/205/35) to a specific CMYK color (22/0/100/8)

      How can i do this? Do i create a profile dor turning my RBG to my specific CMYK)
      How can a i create a custom ICC?

      I know this is probably a lame question... but o really don't find much information about my specific problem!

      Thnsk everybody!
        • 1. Re: Trnasform Specifc RGB color to Specific CMYK color... How to?
          (Marco_Ugolini) Level 1
          Well, if your RGB file is in AdobeRGB, R 194, G 205, B 35 will convert (via Edit > Convert to Profile) to C 23, M 1, Y 100, K 0 if you use as your destination profile U.S. Sheetfed Coated v2, with a Relative Colorimetric intent and with Black Point Compensation checked (if you do *not* check BPC, you get C 24, but the numbers for the other inks do not change).

          These results are *very* close to your target numbers, but only *if* your destination CMYK space/profile is U.S. Sheetfed Coated v2. If, instead, your destination is U.S. Web Coated (SWOP) v2, for example, then you *won't* get those numbers. (Instead you'll get C 31, M 4, Y 100, K 0, still using RelCol + BPC.)

          So, it all depends on the choice of source and destination profiles, as always.

          As for creating a custom ICC CMYK profile that will give you the exact results you are seeking, a profile is not meant to force any arbitrary CMYK numbers for any *one* particular source color. It is solely meant *to preserve the original colors' colorimetry* to the largest possible extent, but the numbers that will generate a given device-independent color on an actual CMYK device *cannot* be chosen arbitrarily, since they are determined by the combination of inks, paper, TRC, gain, etc., when using that given press/device.

          Put in other words, wishing that a certain set of CMYK numbers will produce a certain exact color on a certain CMYK device will not necessarily make it so. Again, it all depends on much more than the numbers.
          • 2. Re: Trnasform Specifc RGB color to Specific CMYK color... How to?
            John Danek Level 4
            Creating an ICC profiles usually requires you to print a zillion swatches that are then read by a spectrophotometer. You can also create a profile for your scanner and your monitor. But, usually it means profiling a piece of hardware. You can also create color profiles using Apples ColorSync application ( this usually involves your monitor ). Your applications also have profiles you can apply ( i.e., Illustrator, Photoshop, InDesign ) in the color setup dialogs.

            Now, if you have known color values ( in your case 194R/205G/35B vs. 22C, 0M, 100Y, 0k ), then you simply input those values into your color palette in the current application at hand. There really is not a profile involved to make the color...just you, the computer, and the application.
            • 3. Re: Trnasform Specifc RGB color to Specific CMYK color... How to?
              Level 1
              Thanks Marco & john.

              The problem is that im making hundreds of PDF´s trough Excel and the program doens´t have CMYK color!

              I´ve tried again and again to find an RGB that would transform to the cmyk i want (its a specif cmyk for a logo).

              How can i do this? is there a way? Script Acrobat? ICC)

              Thanks a lot AGAIN!

              • 4. Re: Trnasform Specifc RGB color to Specific CMYK color... How to?
                John Danek Level 4
                It sounds like you are printing the Excel documents with the logo in place and the color does not match. Color originates in your application ( Excel ) and gets converted in the print driver. So, it may be a matter of setting up several swatches of RGB Lime Greens ( each with a slightly different RGB value ) and printing them on whatever it is you are using as a printer. Then, you can compare your logo to the swatches and choose the one that comes closest. But, like Marco says, some of this may depend on your systems' color settings ( I do not think Excel has a color setup dialog ).