6 Replies Latest reply on Apr 20, 2010 6:34 AM by Meson77

    Confused about converting to profiles and effect on ink values!

    Meson77

      Hi, I wanted to understand what is happening to my ink values when I convert to a different profile. I have set up CS for Europe prepress and am working on an INDD file. All the linked PS images have the same profile.

       

      The printer sent me their profile and has asked to convert all images and the INDD doc. But when I do so, looking at the PS images with the color sampler, it has shifted the ink values. (For example, what was 100K in an image now shows ink in all 4 channels.) This is a problem for me.

       

      In the past I would just convert to the profile at the export>pdf stage which seems to work ok. What should I do? Is there any difference to the printer if I convert at the pdf stage, rather than converting all PS images and the INDD doc?

       

      Thanks in advance!

        • 1. Re: Confused about converting to profiles and effect on ink values!
          John Danek Level 4

          I would try to retain all of the image and document file settings.  So, I'd convert in the PDF.  But, I wonder if there is a way to maintain your original Blacks?  Sometimes, this can be setup in the RIP, as well as "Use Existing Profiles".  You'll have to communicate with the vendor that you want accurate Blacks, eventhough you've supplied their profile as spec'd.  They can do that on their end.

          1 person found this helpful
          • 2. Re: Confused about converting to profiles and effect on ink values!
            Meson77 Level 1

            Hi, thanks for the reply. I guess I'm still not sure on a few issues:

             

            Does converting to a profile actually change the ink values?

             

            What's the advantage of converting to a printer's profile early in the workflow rather than at the export pdf stage? (Does it not mean that you'd have to go back and change all these if, for example, you were to send the job to a different printer at a later date?)

             

            One other thing I don't get - checking the separations in Acrobat all my text is on the black plate only. But when I check the rich black option, it shows that same text as rich black. How can this be?

             

            I know there are a number of color management issues I have yet to understand....!

            • 3. Re: Confused about converting to profiles and effect on ink values!
              John Danek Level 4

              Does converting to a profile actually change the ink values?

               

              In your case, changing the profile in the application, will change the ink values, but it's hard to say how much without comparing the two files.  If you have the opportunity, try changing the profile on a copy of one of your files.  Then, print a contract proof of the file ( if you can ).  You could also check the percentages using some sort of third party application, Acrobat, or Photoshop.

               

              I believe that if you retain your profiles until you create the PDF ( where you will ultimately use their profile in the PDF creation ), then you maintain some control over your original color destination.  A print vendor has created a profile based on their press, a certain type of paper, and has established ( or should have ) the proper total ink densities for that particular press and paper.  In using their profile in the PDF creation, you've given them what they want for their RIP.  It is sort of a way for the vendor to predict the ink amounts they will be getting.

               

              Now,  if you give the same PDF to another print vendor, there may be a "shift", how big or how small is determined by the new vendor's profile.  So, you may not want to hand the same PDF to another printer.  You would be best to obtain the new print vendor's profile and use it in the new PDF creation for that particular printer.

               

              What's the advantage of converting to a printer's profile early in the  workflow rather than at the export pdf stage? (Does it not mean that  you'd have to go back and change all these if, for example, you were to  send the job to a different printer at a later date?)

               

              Yes, it woukld mean changing all of the files to a new destination profile.  There is an advantage if you plan on future jobs all going to that one press using that one type of paper.  This is often referred to as a closed-loop workflow.  In a closed loop workflow, you can optimize ink densities to that one press/one paper and get consistent results.  When you are potentially going to send the PDF to several different vendors, it is referred to as an open-loop workflow.  In an open-loop workflow ( yours ), you use standardized profiles in anticipation for where the printing will be done.  In the case of your vendor who supplies you with their printer profile, you simply create another PDF using their profile while maintaining all of the original application profiles.

               

              One other thing I don't get - checking the separations in Acrobat all my  text is on the black plate only. But when I check the rich black  option, it shows that same text as rich black. How can this be?

               

              I'm not sure what is going on there.  Since your Blacks ( should be ) over-printing, they may be considered Rich Blacks eventhough they are not.  Perhaps if the Blacks were knocking out, then they would be considered Accurate Blacks.  That said, the separations tell the whole story.  If they appear to be Accurate Blacks in the seps, then they should RIP that way.  Another reason to be in touch with the print vendor and make sure you get what you want on press.

              • 4. Re: Confused about converting to profiles and effect on ink values!
                Meson77 Level 1

                In your case, changing the profile in the application, will change the ink values, but it's hard to say how much without comparing the two files.  If you have the opportunity, try changing the profile on a copy of one of your files.  Then, print a contract proof of the file ( if you can ).  You could also check the percentages using some sort of third party application, Acrobat, or Photoshop.

                 

                Yes, it does appear to change the ink percentages, as shown in both separations (Acrobat) and channels (PS). My concern was that I picked colors from a Pantone book and set up the file accordingly: but change profiles and it throws all of the ink values off. Even if the resulting change is negligible to the eye, it represents big problems if – for example – you started with a two color job which, upon conversion, ends up separating into 4 plates.

                 

                In a closed loop workflow, you can optimize ink densities to that one press/one paper and get consistent results.  When you are potentially going to send the PDF to several different vendors, it is referred to as an open-loop workflow.  In an open-loop workflow ( yours ), you use standardized profiles in anticipation for where the printing will be done.  In the case of your vendor who supplies you with their printer profile, you simply create another PDF using their profile while maintaining all of the original application profiles.

                 

                That's good to know, I've been working with open-loop all these years and never knew it. I can see if I were to go the closed loop route, I'd only convert source files to a new profile at the very beginning of the workflow, to avoid complications down the line.

                 

                 

                Since your Blacks ( should be ) over-printing, they may be considered Rich Blacks eventhough they are not.

                 

                I think you're right - seems the Acrobat function counts overprinting blacks as rich, even though the view overprint button is right above it (and a separate option).

                 

                Thanks for your comments, I really appreciate the tech help on offer here.

                • 5. Re: Confused about converting to profiles and effect on ink values!
                  John Danek Level 4

                  My concern was that I picked colors from a Pantone book and set up the  file accordingly: but change profiles and it throws all of the ink  values off. Even if the resulting change is negligible to the eye, it  represents big problems if – for example – you started with a two color  job which, upon conversion, ends up separating into 4 plates.

                   

                  Be careful here, that scenario ( above ) is a Spot color job, not process color.  You should not end up with four plates if you started with two.  That would mean a process color conversion took place.  For example, if you start with 30% 199C + 10% K, but end up with 0%C, 30%M, 21.45%Y, 10%K, then the PDF converted to Process color.  This would have nothing to do with profiles, but rather the way the PDF was created.  What should happen is you get 2 plates on output in Spot Color jobs, not 4.

                   

                  That's good to know, I've been working with open-loop all these years  and never knew it. I can see if I were to go the closed loop route, I'd  only convert source files to a new profile at the very beginning of the  workflow, to avoid complications down the line.

                   

                  Correct.  I worked several years in a closed-loop workflow where I calibrated the RIP and, in the RIP, used a custom profile I built in calibrating the printer and aper combination.  I was able to determine the correct amount of Total Ink for that given media, and, theoretically, also determined the correct amount of Process Color inks to match most of the Pantone Color System.  This was achieved using a spectrophotometer which generated the .icm printer profile which could then be used in the RIP when processing files.  Hypothetically, the same profile could be used to maintain the ink densities for a Spot color job whereas a 30% 199 + 10%K would RIP and the result could be 22% 199 + 7.5%K, but when printed would result with a 30% 199 + 10% K based on ink densities and dot gain on press via a custom .icm profile.

                   

                  Things get a little more complicated in an open-loop workflow.  Should you determine that all of your files will be converted to working CMYK = SWOP Coated and your color settings are based on 20% dot gain, Use Black Point Compensation and have a Relative Colorimetric Rendering Intent ( a US standard ), then your file should be OK to RIP on virtually 90% ( let's hope ) of the presses out there.  Now, each print vendor is going to have, in place, a calibrated RIP that can deall with most files and produce consistent results across the board.  That's the dream of color management.  Have we reached that yet?  Good question.

                  • 6. Re: Confused about converting to profiles and effect on ink values!
                    Meson77 Level 1

                    Be careful here, that scenario ( above ) is a Spot color job, not process color.  You should not end up with four plates if you started with two.  That would mean a process color conversion took place.

                     

                    Ah, I was actually using all process colors throughout (using the Pantone process book) - e.g. 100K that would have created registration problems if separating into 4 plates (since I had small reversed out type). Converting the linked PS files to the new profile actually split that 100K black into 4 channels/separations.

                     

                    Should you determine that all of your files will be converted to working CMYK = SWOP Coated and your color settings are based on 20% dot gain, Use Black Point Compensation and have a Relative Colorimetric Rendering Intent ( a US standard ), then your file should be OK to RIP on virtually 90% ( let's hope ) of the presses out there.  Now, each print vendor is going to have, in place, a calibrated RIP that can deall with most files and produce consistent results across the board.  That's the dream of color management.  Have we reached that yet?  Good question

                     

                     

                    Yes, I've also found in 90% of cases that my printers are generally happy to take files with the standard Euroscale settings (I'm in the UK). Only occasionally with a new printer will I be given a new profile. I guess, as a designer, I've been happy (and possibly lazy) to leave most of the fine details of RIP to them, and tend only to get involved if a specific problem arises. In an ideal world I'd buy a big book on color management and educate myself more fully, but there's always more doodling to do........