15 Replies Latest reply on Feb 28, 2008 3:19 PM by Ramón G Castañeda

    Why 'preserve numbers' for cmyk policy

    Level 1
      Hello,

      I am at a loss why Adobe InDesign CS3 advises you to use the setting 'Preserve numbers (ignore linked profiles)' in 'Color Management policies' as a safe cmyk-workflow. Wouldn't it be more logical to 'Preserve embedded profiles'? This way your InDesign document has its own working space profile embedded for contents created in the document itself and it would contain the profiles of placed content. This way nothing can go wrong (well, nothing...).

      Any ideas?

      Cheers,

      Johan
        • 1. Re: Why 'preserve numbers' for cmyk policy
          (Aandi_Inston) Level 1
          Well, it depends how you think about CMYK. For many people CMYK values
          are what they expect to end up on press; color management is therefore
          something they essentially want to disable for CMYK values. The loss
          of overprinting, rich black and other plate-specific effects is seen
          as undesirable.

          Aandi Inston
          • 2. Re: Why 'preserve numbers' for cmyk policy
            Level 1
            Hi Aandi,

            Thanks for your answer, but I still have one more question. Why would turning on colour management result in loss of overprinting or rich black? Shifts in the CMYK-numbers due to colour managed profile conversions should result in the same 'colour experience'. In other words isn't it the entire idea of colour management that the CMYK-numbers are tweaked in such a way that the result will be constant in whatever output you create (be it print or display); so the appearance of your rich black shouldn't change even if the CMYK-numbers change slightly due to a conversion?

            I'm curious as to what your ideas are.

            Best,

            johan
            • 3. Re: Why 'preserve numbers' for cmyk policy
              Lou Dina Level 3
              Johan,

              If you use the exact same profile as your final destination device, there will usually not be a color conversion done by your service provider. This way, your numbers remain unchanged.

              However, if they do any conversions at all, they will have to pass from a 4/C CMYK space to a 3 color profile connections space (usually Lab), and then to the new CMYK space. Since the intermediate space is 3 color, it cannot retain black generation information (some software can handle these components separately, though). As you enter the new CMYK space, black will be regenerated and this could turn your black text, lines and other design elements into CMYK black as Aandi mentioned. Conversion can be good things for images and some elements, but a major problem for lines, text, and components that you absolutely do not want changed.

              Lou
              • 4. Re: Why 'preserve numbers' for cmyk policy
                Level 1
                > For many people CMYK values are what they expect to end up on press; color management is therefore something they essentially want to disable for CMYK values.

                The question should not be "What CMYK values do you want?" Instead the question should be "What color appearance do you want?" The umbrella operating principles of CMYK printing are moving (albeit slowly) from a number-based approach to an appearance-based approach.

                I agree with the OP that "safe-CMYK" in InDesign is anything but. The notion that clicking "Preserve Numbers" will assure you of exercising control over your color is outmoded. A given set of CMYK values will print six different ways on six different presses. Gracol (G7) has offered a giant step forward towards standardizing press output, but it's only a first step. It is true that one of the things holding back wider acceptance of color management in the pre-press community is the loss of black-only elements during a conversion. There are answers to that problem (device-link profiles.)
                • 5. Re: Why 'preserve numbers' for cmyk policy
                  Level 1
                  When will Photoshop and InDesign support Device Link Profiles, which would address this problem?

                  I guess since I prep my files for specific outputs prior to importing them to Xpress or ID, I really do want to preserve the numbers.
                  • 6. Re: Why 'preserve numbers' for cmyk policy
                    Level 1
                    I've been trying to determine the derivation of the term "Safe-CMYK" in whcih numbers are preserved. When looking at image files, it's certainly not safe - numbers stay the same, but appearance changes. However, when looking at text and other k-only elements, it is safe - i.e. those elements are not converted to 4-color, rather, they stay k-only. So this highlights the need on the Creative Suite for device-link profiles.
                    • 7. Re: Why 'preserve numbers' for cmyk policy
                      (Aandi_Inston) Level 1
                      Bear in mind that overprinting is essentially a printing artefact, not
                      a colour.

                      For example, you may want black to overprint your C,M,Y plates to
                      avoid registration issues, but this is nothing to do with colour. The
                      colour remains black. Therefore this rich black or overprinted area
                      will be turned into Lab (or the similar CIEXYZ), then back to CMYK.
                      This will use the default amount of black generation, perhaps none, so
                      printing artefacts could reappear.

                      Also, consider the rather worse case where you have fine lines in
                      black. Converting these to a different CMYK profile will result in
                      delivering black generation, so for most target profiles these black
                      lines will now have a certain amount of C,M,Y. This is also a problem
                      for scanned text, and for text itself unless the application
                      specifically eliminates this case.

                      Aandi Inston
                      • 8. Re: Why 'preserve numbers' for cmyk policy
                        Level 1
                        > Bear in mind that overprinting is essentially a printing artefact, not
                        a colour.

                        Excellent point. Printing artifact vs. color is a good distinction to keep in mind as we think through this issue.
                        • 9. Re: Why 'preserve numbers' for cmyk policy
                          Level 1
                          There are other reasons that "Safe-CMYK" preserves numbers. Many people do their color management by converting to the correct CMYK profile in Photoshop, before an image gets to InDesign. They do not want these CMYK values changed when the image is output. Others apply device link profiles at the RIP, which occurs AFTER being output. These people also want InDesign to output the CMYK values that they started with

                          Although color management is a wonderful thing, let's not forget that most printers still want "final" CMYK files. Most printers are not going to re-separate or re-purpose your CMYK files, so you really don't want to do it when you are proofing.

                          If everyone was on-board with color management, and everyone embedded profiles in their images, and every printer respected those profiles, then "Safe-CMYK" would not be necessary. But then, if everyone were on-board with color management, no one would even have to save out CMYK images - you would just use RGB images and have the conversion happen upon output. That would ultimately yield the best results. So the question really isn't "why is there a safe-CMYK workflow?", but "why are you saving your images in CMYK in the first place?" You are saving CMYK images because that is what the printer or pub has requested, and those exact CMYK seps are what they are going to use.

                          So there really are a lot of reasons you might want InDesign to ignore profiles and just output the CMYK values that were brought in. Will this yield the color appearance you have specified in your profile? Maybe not, but it will be a proof of the CMYK numbers you started with, which are quite likely what are going to press.

                          -Todd Shirley
                          • 10. Re: Why 'preserve numbers' for cmyk policy
                            (Marco_Ugolini) Level 1
                            At the risk of sounding overly sarcastic, the only thing that "safe CMYK" is safe for, it's for print providers who refuse to update their workflows, so that they can deflect blame on to everyone else.

                            There is no reason why it shouldn't be safe to use *color-managed* workflows instead. It's only because of this persistent resistance from so many print providers that we resort to a "safe CMYK" tactic that is still anything but completely "safe" anyway, when all is said and done.
                            • 11. Re: Why 'preserve numbers' for cmyk policy
                              Level 1
                              Marco, I think we've had this debate before, and I stated it pretty clearly in my previous post as well: Most prepress shops and printers that I deal with DO use a *color-managed* workflow, they just don't want the color management happening in InDesign, so the "safe CMYK" workflow is what we use. As I mentioned before, either the color management is taking place in Photoshop BEFORE it gets to InDesign, or in the RIP, AFTER it comes out of InDesign.

                              If a shop has a locked-down color management workflow (which we do), it is necessary to control all stages of production. One way to do so is to make sure your layout program isn't changing the CMYK values of images when it sends them to the RIP. Using color management in InDesign is a perfectly reasonable workflow as well, but its my experience that it is more controllable to perform color management at other points in the workflow. I have several InDesign operators with varying degrees of experience, as well as freelancers, and it is MUCH safer to have them use the "safe CMYK" settings.

                              We are just a prepress shop, not an actual print provider, but we do update our workflows, we don't deflect blame to others (we don't have to, because our color-managed files work great on press), and this is indeed a safe workflow.
                              • 12. Re: Why 'preserve numbers' for cmyk policy
                                (Marco_Ugolini) Level 1
                                No need to feel defensive, Todd. Your company uses color-managed workflows, so kudos to you and your colleagues.

                                I'm talking about the ones who "proudly" refuse to innovate. Those I have no kind words for.
                                • 13. Re: Why 'preserve numbers' for cmyk policy
                                  (Aandi_Inston) Level 1
                                  For an interesting take on this problem, and especially the problem
                                  that people have getting a handle on the real meaning of colour
                                  management, here is a discussion in a different forum:
                                  http://forum.planetpdf.com/scripts/wbpx.dll/read?164712,106e#164712

                                  In essence, the question there is, I believe "We work with this CMYK
                                  color space; someone sent us work using a different colour space. The
                                  color changed. They complained. Whose fault is it?" I've found
                                  responding challenging, and would welcome any critique of my answers.

                                  Aandi Inston
                                  • 14. Re: Why 'preserve numbers' for cmyk policy
                                    Level 1
                                    PDF = Portable Document Format.

                                    What you supply is what you get. The person who generates the PDF is liable. If the printer generates it - they are responsible. If the client generates it - they are responsible. The problems come into play when terms and conditions are not spelled out in detail. Most business practices do not follow hard lines because you will lose customers if you are a hard liner. Most clients don't take responsibility for their own art because they usually are not sure of anything that they create - and compiled with the lack of process control within applications as well as print processes, who in their right mind would want to.

                                    In other words, pray.
                                    • 15. Re: Why 'preserve numbers' for cmyk policy
                                      Ramón G Castañeda Level 4
                                      >In other words, pray.

                                      Hmmm I guess non-believers have no place in this business. :D