24 Replies Latest reply on Feb 8, 2014 8:40 AM by rob day

    Pantone Halos

    StarvingArtist Level 1

      A maddening InDesign mystery: When any blurred or feathered image is placed over a Pantone color it takes on a disturbing halo when viewed in the Overprint Preview. This does NOT happen when the same image is placed on cmyk colors.

        • 1. Re: Pantone Halos
          Sandee Cohen Adobe Community Professional

          Can you provide a screen shot?

           

          What are your color settings?

           

          Does the halo print?

           

          There are too many variables to speculate.

          • 2. Re: Pantone Halos
            StarvingArtist Level 1

            Does the halo print? Yes, the million $ question. If it does I certainly don't want to go the Pantone route. But not even my printer can give me a straight answer about this issue.

             

            The halo is there regardless of the color settings.

             

            Screen shots: Overview Preview on (first one), Overview Preview off (second one). Notice the dark blue halo around the first one?

             

            ScreenShots.jpg

            • 3. Re: Pantone Halos
              rob day Adobe Community Professional & MVP

              If it does I certainly don't want to go the Pantone route. But not even my printer can give me a straight answer about this issue.

               

              Is the Pantone color going to print as an extra spot color—does it show up as a color in Sep preview? If you don't plan on printing it as a spot set it to process in Ink Manager or use Pantone + Bridge colors, which are process colors.

              • 4. Re: Pantone Halos
                StarvingArtist Level 1

                It's printing 5 colors: cmky + a 'spot' pantone color, and shows up as such in the Acrobat preview.

                • 5. Re: Pantone Halos
                  rob day Adobe Community Professional & MVP

                  I looks like the object on top of the Pantone background has some transparent pixels along the edge of the silhouette? If that's the case the Overprint preview would show the transparent CMYK pixels trapping  to the spot color background.

                  • 6. Re: Pantone Halos
                    StarvingArtist Level 1

                    Yes, blurred/feathered edges have transparent pixels, but there is no good reason for a dark halo. It doesn't occur when the same image is placed on a cmyk background.

                    • 7. Re: Pantone Halos
                      rob day Adobe Community Professional & MVP

                      but there is no good reason for a dark halo.

                       

                      I think it's unavoidable as the 5th color traps to the CMY. With all process you wouldn't need much of any trap. Even if you eliminate the transparent transition pixels the 5th color would have to trap to the CMY and you would get a trap line.

                      • 8. Re: Pantone Halos
                        rob day Adobe Community Professional & MVP

                        What's the pantone color? From your screen capture it looks like it's in the CMYK gamut, so why bother with the spot color?

                        • 9. Re: Pantone Halos
                          StarvingArtist Level 1

                          Why would a Pantone background need more trapping than a cmyk background? The same butting of colors, red against blue, is happening either way.

                          • 10. Re: Pantone Halos
                            StarvingArtist Level 1

                            The diffence between Pantone 2817 and the cmyk equivalent could make a designer weep.

                            • 11. Re: Pantone Halos
                              rob day Adobe Community Professional & MVP

                              Why would a Pantone background need more trapping than a cmyk background?

                               

                              If you look at the problem area of your example there's no need for a trap if the colors are process because it isn't red against blue. When its a process forground on the spot back ground you'll have to have some combination of spot + CMY as the trap whether the colors are similar or not.

                               

                              So an extreme example would be something like 80% cyan on 100% of your Pantone Blue. If everything is process no trap would be needed, but with 80% cyan on top of 100% spot blue you would need a trap line of 80% cyan + 100% spot blue

                               

                               

                              Untitled-1.png

                              • 12. Re: Pantone Halos
                                StarvingArtist Level 1

                                If everything is process no trap would be needed

                                 

                                Are you saying there would be no trapping involved if it was all cmyk?

                                • 13. Re: Pantone Halos
                                  rob day Adobe Community Professional & MVP

                                  Here's an example of a PDF made via Distiller that includes traps generated via InDesign's built-in trapping—I've exaggerated the default trap width so it would be obvious.

                                   

                                  On the left is 29|23|0|0 on a spot Pantone 2718. The trap line is obvious because it's 29cyan, 23magenta, + 100% 2718

                                   

                                  On the right both boxes are CMYK—the background is 62|36|0|0. In this case there's no trap because neither color has black or yellow.

                                   

                                  ScreenSnapz001.png

                                  • 14. Re: Pantone Halos
                                    StarvingArtist Level 1

                                    Your box has no feathered edges, and you've chosen colors that aren't that disimilar. Most of the color butting in my image will be strong red against strong blue.

                                     

                                    PS- you've circled a white-ish area your previous post, and though that's the where it's most evident the dark halo goes all the way around the image.

                                    • 15. Re: Pantone Halos
                                      rob day Adobe Community Professional & MVP

                                      and you've chosen colors that aren't that disimilar.

                                       

                                      Right I'm showing that trapping or the interaction with transparency will be more obvious with a spot color than with process.

                                       

                                      When process colors are similar there might not be a trap, but there always has to be a trap between a spot color and a process color even if they have the same color appearance.

                                       

                                      You're effectively creating a manual trap by overlaying transparent CMY pixels on a spot color.

                                      • 16. Re: Pantone Halos
                                        StarvingArtist Level 1

                                        Rob, I'll have to think about your last reply some more. 

                                         

                                        Will that dark halo show up when it's offset printed?

                                        • 17. Re: Pantone Halos
                                          rob day Adobe Community Professional & MVP

                                          I don't see how you avoid some kind of trapping between the spot and CMY. I think you have to talk to the printer about how the process and spot will trap.

                                          • 18. Re: Pantone Halos
                                            StarvingArtist Level 1

                                            There will be trapping (done correctly in Illustrator according to my printer) but does trapping = dark halo just as the preview shows?

                                            • 19. Re: Pantone Halos
                                              rob day Adobe Community Professional & MVP

                                              but does trapping = dark halo just as the preview shows?

                                               

                                              I doubt you'll get a perfectly blended transition with the spot color. The only way to know is with a press proof.

                                              • 20. Re: Pantone Halos
                                                rob day Adobe Community Professional & MVP

                                                just as the preview shows?

                                                 

                                                One thing more about this, InDesign doesn't have full color managment for spot color percentages. So even if you have a well profiled monitor and your document CMYK profile is accurate for the press, spot color percentages and certainly spot+CMYK mixes can't be reliably soft proofed.

                                                 

                                                So your halo might not show (or it could be worse).

                                                 

                                                Here I'm replicating the blend problem and viewing the edge percentages in Sep Preview, which are reading as 4|12|2|0 + 87. I don't think ID is capable of accurately soft proofing that 5-color ink mix.

                                                 

                                                 

                                                ScreenSnapz002.png

                                                • 21. Re: Pantone Halos
                                                  StarvingArtist Level 1

                                                  I guess that's also the case with Illustrator?

                                                  • 22. Re: Pantone Halos
                                                    rob day Adobe Community Professional & MVP

                                                    Yes.

                                                     

                                                    CS6+ forces you to use the more accurate Lab color definitions for the Pantone + libraries, so soft proofing 100% of a Pantone color is  managed, but when you get into percentages there's no Spot color Working Space as in Photoshop where you can at least adjust the preview with a expected dot gain curve. Mixes are even more problematic because there has to be an assumption about what color would be created when the spot and process colors overprint.

                                                    • 23. Re: Pantone Halos
                                                      StarvingArtist Level 1

                                                      Why doesn't photoshop have some way to work with Pantone backgrounds as layers? A Pantone alfpha channel does me little good.

                                                      • 24. Re: Pantone Halos
                                                        rob day Adobe Community Professional & MVP

                                                        to work with Pantone backgrounds as layers

                                                        Because Photoshop pixels are restricted to one color mode—you can't mix color spaces.

                                                         

                                                        It would also create an impossible color management problem. CMYK profiles are made by taking color readings off of printed press sheets, so for example we can softproof the expected differences between US Sheetfed and Euroscale before going to press. That would be logistically impossible if custom color and process combinations had to be considered and profiled.