7 Replies Latest reply on Nov 3, 2008 6:03 AM by stevenwild

    cmyk formulas


      I'm looking for advice regarding the use of cmyk to create Pantone-equivalent colours. Every time I try to use a cmyk breakdown of a Pantone colour, I'm always unsure whether to use the cmyk values on my Pantone Colour Bridge fan, or the cmyk values provided in the relevant Creative Suite application.

      For example - Pantone 653C.

      Bridge = c96, m59, y4, k17

      InDesign/Illustrator Pantone Solid Coated swatch = c100, m62, y0, k20
      InDesign/Illustrator Pantone Solid to Process swatch = c100, m62, y0, k20

      Photoshop Pantone Solid Coated swatch = c88, m68, y14, k2
      Photoshop Pantone Solid to Process swatch = c100, m62, y0, k20

      If anyone can give me an idea of the best cmyk to use when reproducing Pantone colours, I'd be most grateful.

      I'm currently using CS2.


        • 1. Re: cmyk formulas
          stevenwild Level 1
          Another question -

          If the consensus is that Bridge values should be used, how do you go about reproducing tints of the Pantone colour? What values do you use?
          • 2. Re: cmyk formulas
            (Marco_Ugolini) Level 1
            First of all, CMYK comes in many flavors. There is "SWOP" Coated and Uncoated, there is Sheetfed Coated and Uncoated, there is GRACoL (yes, Coated and Uncoated), there is newsprint, and so forth.

            In other words, there is no
            i one
            "CMYK". So, one needs to start off by defining which CMYK one is targeting.

            Once you know which instance of CMYK is your target, you can use Photoshop to produce appropriate CMYK equivalents.

            Open a new file in Lab color mode. Set your foreground color to the Pantone color you are intending to simulate in your printed piece. Fill the canvas of the open Lab image file with the chosen foreground color.

            Now go to Edit > Convert to Profile, choose your destination CMYK under "Destination Space", then set the rendering intent to Absolute Colorimetric (to account for the substrate of the chosen CMYK color space). Click "OK", then sample and write down the CMYK numbers in the resulting image: those will be the ones to use for best results in the destination CMYK.

            As for tints, in Illustrator create a global process swatch using the CMYK numbers you produced in Photoshop. Apply the swatch color to a vector object and screen it to the desired amount. Then use the Color panel to release the CMYK numbers for that tint of the global process color swatch.
            • 3. Re: cmyk formulas
              John Danek Level 4
              It's interesting that CS's CMYK's are all the same ( 100C, 62m, 0y 20k ), which matches Pantone's Solid-to-Process equivalents ( er, per my swatch books that were produced before Pantone's recent remix [ Bridge ] and new GOE system ). I agree with Marco, there are a few new choices out there. One of your considerations should be the output device. Are you in a closed loop workflow where the file will be printed inhouse ( i.e., inkjet proof )? Or, will you be sending the file outside ( open loop workflow )? I ask because in a closed loop workflow, you could run tests using your particular printer/proofer, where you could create a series of swatches with percentages of 2% deviations and see which swatch comes closest to your Pantone Spot color swatch. If you plan on going open loop, contact the shop that will print the job and consult with them which CMYK deviate to use. Chances are, they'll have you use the standard Pantone Solid-to-Process percentages.

              In creating tints, I ususally create the initial swatch in Illustrator: 100C, 62M, 0Y, 20k. Then, I hold the Shift key and drag one of the sliders [ Cyan ] down to 80%C ( all of the other sliders follow if you hold the Shift key ) and drag that swatch to the Swatch palette ( from the Color palette ). Do this again for 60%, 40%, and 20% for a total of 5 swatches. If you're looking for 5%C, 7.5%C, 10%C, or any other deviation, just remember to hold the Shift key when dragging the slider around and all of the percentages will remain intact. That's how I do it.

              There's nothing wrong with Pantone Bridge, or GOE, or any other CMYK deviate, as long as they match the original Spot color. In your case, its Pantone 653. If you'll notice, the numbers are only off about 3%, not really significant...but, who knows?
              • 4. Re: cmyk formulas
                stevenwild Level 1
                Hi Marco, thanks for the suggestions. I'll definitely give your ideas a go. I'm using coated (Pantone 653C) spot colours.

                John, thanks too for your ideas. Do you think that Pantone's change of cmyk formulas (ie from your old swatches to Bridge), and the fact that they no longer match up with the Creative Suite values, means that Pantone's swatch formulas are more accurate than CS?

                Unfortunately I use an external printer, otherwise your 'print and check' method makes sense. I'll just talk to the printer and see what they suggest.

                Thanks again to you both.

                • 5. Re: cmyk formulas
                  (Marco_Ugolini) Level 1
                  >Do you think that Pantone's change of cmyk formulas (ie from your old swatches to Bridge), and the fact that they no longer match up with the Creative Suite values, means that Pantone's swatch formulas are more accurate than CS?

                  The question that one must ask is: more accurate for what kind of output, exactly?

                  The method that I indicated, when properly executed, is, in my view, the most flexible and accurate one available -- as long as you have an ICC profile handy that closely reflects the specific output conditions on press, or at the very least the general print conditions that the printer pledges to match on their own presses, such as U.S. Web Coated (SWOP) v2, for example.
                  • 6. Re: cmyk formulas
                    John Danek Level 4
                    Steven, I believe Pantone decided to update some of their formulas, but all of the swatch formulas are based on offset printing parameters ( Heidelberg ) on the specific type substrate ( i.e., coated, uncoated, matte ). Pantone lists the print parameters they use in developing their formulas in some of their documentation.

                    Of late, it's become more challenging to keep up with Pantone's developments with the recent release of colormunki, GOE, and Bridge. Now, I have an inhouse proofer that does the Pantone color transformation in the RIP, so you do not have to specify anything more than the Pantone 653 in your application, and the RIP does the conversion. So, hypothetically, you do not have to use the CMYK build in the application. Instead, just specify the 653C or any tint of that. The advantage is that you can supply your vendor the original Spot color file which, by happenstance, you also fed through your proofer. I do know ( I printed out the supplied tables ), that the CMYK equivalents used by my proofer's RIP are 96C, 59M, 4Y, and 17K, which are very close to the Bridge numbers you list in your post.

                    I would stay with the CM2 Pantone numbers unless your print vendor prefers the Bridge numbers. As is usually the case, the vendor is the one who decides and you build your file in compliance to their workflow(s). This is key, you should be in constant communication with your vendor from concept to final disk delivery to them. Alot depends on their workflow.
                    • 7. Re: cmyk formulas
                      stevenwild Level 1
                      Thanks very much for your reply John. Your suggestion of talking to the printer makes a lot of sense, and is something I can occasionally do. Unfortunately I work for a company that has offices around the world, so oftentimes I have no information about the printer or their processes.

                      Thanks again for your advice.