3 Replies Latest reply on Jun 29, 2014 5:12 PM by rob day

    Why do I get two different RGB equivalents for one CMYK color?

    ashmath34 Level 1

      I’m helping someone incorporate their blue logo into business cards and a branding guide. The Illustrator file they gave me of their logo is set to the CMYK color space, so I used these CMYK values for their branding guide. When I click on the RGB tab to see the converted values for the CMYK color, they are insanely different from the RGB equivalent I get when using an online color converter, like Adobe Kuler. In both InDesign and Illustrator, the CMYK values for the blue logo are 79, 56, 2, 0 and when I click on the RGB tab in InDesign or Illustrator, these programs tell me that the RGB equivalent is 69, 112, 179. However, when I use the Adobe Kuler website and plug in the CMYK values, the website (and other websites like it) tell me that the RGB equivalent to this CMYK color is actually 54, 112, 250. I’m not sure which RGB value is actually correct.

       

      That said, I tried plugging in the RGB values I get from the design software into the Adobe Kuler color converter, and I get totally different CMYK values than what the design software tells me. Which color values do I include on the client's branding guide?


      I've heard that blue colors are notoriously hard to convert between RGB and CMYK, and I'm wondering if that's why I'm getting these drastically different values from different color conversion tools. I've also read that different ICC profiles might affect the CMYK/RGB values in the design program, but I'm not well-versed in this. Please help!!

        • 1. Re: Why do I get two different RGB equivalents for one CMYK color?
          Steve Werner Adobe Community Professional & MVP

          I've moved this to the InDesign forum because that was one of the two programs you mentioned using. It's much more likely to get answer from the color geeks here that in the Creative Suite forum.

          • 2. Re: Why do I get two different RGB equivalents for one CMYK color?
            Willi Adelberger Most Valuable Participant

            The colormanegement in the Creative Suite/Cloud calculates different values depending on the profiles you have used.

            1. Your input color mode is CMYK
            2. You did not mention your input Color Profile, only if the color mode and color profile is known and specified you have a specified color, with different input profiles in CMYK you will get differen colors.
            3. Your output color mode is RGB, but if you convert into different RGB color spaces you will get different values. So you have to determine the correct RGB color space, you  need to choose a color profile.

            A lot of internet color calculators are missing these important facts, so the calculated values are not relevant.

            If you want to show RGB colors correct in the Web or in MS Office (like PowerPoint presentations) you might choose sRGB as output profile. But take care that you have chosen the correct CMYK profile first.

            • 3. Re: Why do I get two different RGB equivalents for one CMYK color?
              rob day Adobe Community Professional & MVP
              the CMYK values for the blue logo are 79, 56, 2, 0 and when I click on the RGB tab in InDesign or Illustrator, these programs tell me that the RGB equivalent is 69, 112, 179.

               

              69|112|179 is the conversion you'll get using the default North American General Purpose Color Settings—or US Web Coated SWOP v2 converted to sRGB. As Willi implies there are many flavors of CMYK and RGB so different sources and destinations, as well as the conversion intent, will produce different results.

               

              So "branding" color this way doesn't really work because 79|56|2|0 CMYK will look very different on newsprint than it will on a GRAcol profiled press with glossy paper, and 69|112|179 RGB will look very different in a CC app with a ProPhoto RGB assignment then it will look in a web browser with no profile assigned.

               

              The best you can do is qualify the values—79|56|2|0 US Web Coated (SWOP) v2 CMYK = 69|112|179 sRGB IEC6196-2.1 RGB