10 Replies Latest reply: Dec 22, 2010 3:28 PM by Semaphoric RSS

    RGB to CMYK, pantone spot color help

    TF22Raptor2 Community Member

      Hi guys,

      I'm not sure if I have a problem with my color setup or my end result will come different than what I see on display, or if its just that I don't have too much pantone print/spot color experience but I can't remember having this issue too much before.

      I have created a bunch of graphics for a website, which now have to be converted to CMYK for print. After I convert the color profile from RGB to CMYK, the main blue I use and all of that blues related tints/highlights and shadows are WAY out. Basically when I look at the Pantone Color Bridge if you look at blue 2935C (which is the correct blue) after converting to CMYK you see that awful dull PC version of the blue as shown in the Color Bridge which is as expected.

      However when I load up the Pantone solid coated swatches in photshop the swatch itself looks about the same as what I see on the printed pantone color chip but when I use the swatch on graphics on my piece of work the color looks more flat/dull lifeless blue. Is this what is meant to happen? I just ignore what the computer output is giving me?

      And does this mean I have to use a spot color to specify the good 2935C in this piece of work?

      If so is there an easy way to specify/change the yuk blue to the good blue on all my layers? As I have a whole bunch of them.

      Any help or advice would be great

        • 1. Re: RGB to CMYK, pantone spot color help
          Mylenium MVP

          You really need to read up on print production! First, the only way to print a spot color as a spot color is to define it as such, meaning Multichannel mode. otherwise there may never be a way to retain the colors in basic CMYK composite mode, since CMYK has a much lower gamut range. Second, conversion of the colors also depends on your color profile settings. If those are not correct, the result will get even worse. Still, in any case, the behavior you see is expected. You just have your workflow completely wrong. All areas that are supposed to be blue will have to be isolated and adjusted separately, but that really comes down to what you actualyl need to do. Also note, that "bright" colors in print almost always are printed with reduced densities/ opacities, so more light reflects from the paper. You may also need to do that, in particular if you only have composite CMYK and cannot use genuine spot colors...



          • 2. Re: RGB to CMYK, pantone spot color help
            p_d_f Community Member

            I looked at 2935C on my Artisan earlier, and while it is certainly a deep saturated blue, it didn't lose nearly as much as I thought it might when converting to CMYK. When you say it looks dull and lifeless, what CMYK profile were you converting to or previewing in? That can make all the difference in the world, and of course, you do have to use the correct profile for the job.


            My guess, and this is from printing thousands of CMYK print jobs in the last fifteen years, is that you can print that color with normal inks and be more than happy with it. What you see on the printed page will look just fine. Yes, it will be slightly duller than your computer screen, but it's not going to be so far off that people will scream. Now, if your client absolutely insists, you can do a spot fifth color, but for this I doubt it's worth the effort or the money.


            Also - the perception of how "blue" a color looks in print is greatly affected by what is next to it on the page. If you have a bright yellow or orange, that extra color contrast will trick your eye into believing that the blue is bluer and more saturated than it really is. This is the kind of trick professional designer and prepress professional use all the time to same time and money on press and deliver jobs that their clients love.


            After you do convert to CMYK, it's always a good idea to use the Selective Color tool and see if minor tweaking to the colors you're interested in can add the proper spice to the recipe. For blues, it's making sure that you've got enough Cyan, usually between 90 and 100 percent and keeping a sharp eye on the Magenta, which can range anywhere from 50-ish to 70-ish. You generally want to fudge the Magenta down rather than up, as blues on press almost always want to pick up more magenta and look too purple as a result.


            Good luck.

            • 3. Re: RGB to CMYK, pantone spot color help
              Reynolds (Mark) Community Member

              To repeat what Millenium has correctly said TF22Raptor2 and p_d_f - Pantone colors and CMYK are not interchangeable. It is not possible to convert a Pantone color to CMYK accurately.


              Why is this this the case? 1. Because printing conditions are too variable for that. The color values in any CMYK file will print totally differently on a different printer. In real terms, CMYK values mean nothing accurate, and refer only very loosely to color. Pantones on the other hand refer to very specific measurable colors under specific lighting conditions. 2. The gamut (range of colors) available in CMYK is much too narrow to include some of the highly saturated colors available in a Pantone book.

              • 4. Re: RGB to CMYK, pantone spot color help
                TF22Raptor2 Community Member

                Hi guys thanks for the responses. Yeah all the other print jobs I've done in the past after converting from RGB to CMYK I guess the colors have been pretty well in the gamut. This time however this is what I am getting.




                Good RGB blue on left, CMYK blue on right. Now to me that is a fair difference there. To me it your traditional happy sky blue on left, and dull winter blue on right.


                My working space for cmyk is US Web Coated SWOP v2


                Any help on getting this blue to be more like the left (without having to use a SPOT color) would be great. (I'm not even sure the printer is going to let me use a SPOT color)

                • 5. Re: RGB to CMYK, pantone spot color help
                  Chris Cox Adobe Employee

                  You do realize that CMYK can't print saturated reds, green or blues, right?


                  Yes, if a color is out of gamut, it will lose some saturation, and may change lightness a little.


                  Have you tried the gamut preview on your RGB image to see what colors are out of gamut for your chosen CMYK profile?

                  • 6. Re: RGB to CMYK, pantone spot color help
                    TF22Raptor2 Community Member

                    Hi Chris,

                    Yes I have done the gamut preview and have also gone to color range, view out of gamut colors and yes my blue on the left is out of range. I then try to replace those out of gamut color blue with one that is closer to what I am after (this is where I specified the Pantone color 2935C, in the swatch on the computer it looks like what it looks like in my color chips, but when I use that color in the actual artwork itself it looks like the desatured blue to the right i showed.

                    So I don't know wheather I just ignore that?

                    • 7. Re: RGB to CMYK, pantone spot color help
                      Mylenium MVP

                      You are running in circles, frankly, because you do not understand the difference between sport color printing and composite CMYK it would seem. Unless you print your blue from a separate plate where it is used directly out of the pantone mixing pot (i.e. physically mixed/ pigmented at the ink paste level), it wil lalways lose saturation. Your whole workflow therfore is unsuitable to retain these colors properly. You really must create a separate selection for this particular blue, store it as a custom channel in a multichannel doc and simply ignore the screen simulation for CMYK. This will only fully unfold when it's printed (assuming your printer provides these options).



                      • 8. Re: RGB to CMYK, pantone spot color help
                        TF22Raptor2 Community Member

                        Hello Mylenium,

                        Yes this is what I thought. (Ignore the onscreen simulation). Am seeing even if the printer can do spot colors. (they are a digital printer).

                        • 9. Re: RGB to CMYK, pantone spot color help
                          Reynolds (Mark) Community Member
                          Am seeing even if the printer can do spot colors.

                          No it can't. Spot colors are specific mixed inks, produced by manufacturers in an attempt to create reasonably precise VISUAL values. An impossible task, because the lighting conditions by which any printed color is viewed, varies so much.


                          The truth about color and color accuracy is as follows: all color perception is relative. We only perceive color based on surroundings. Precisely the same measurable red will appear differently based on its context. Our eyes, filtered through our brains, adapt the way we perceive color all the time. Many years and many idiots trying to prove otherwise has proved only one thing, color itself is not a nailed down set of rules. Very philosophical.

                          • 10. Re: RGB to CMYK, pantone spot color help
                            Semaphoric Community Member

                            I think Raptor means "they" the printer, not "it' the printer.