13 Replies Latest reply on Sep 21, 2011 10:12 AM by WBTxTx1

    NChannel Question from InDesign

    WBTxTx1 Level 1

      When I place a PDF file as a n image  in InDesign, then export diretly to PDF, my  PDF files are coming out with NChannel in them.

       

      The printer rep tells me NChannel an undefined spot color that does not convert to gray correctly, and therefore is not allowed in the final PDF I send to them.

       

      NChannel is not present in the PDF which I place into InDesign as art. InDesign is converting elements of the PDF I am placing from gray 0% brightness to NChannel when I export to PDF.

       

      If I print to post script from InDesign, then distill, I get no NChannel problems, however, the printer only recommends exporting to PDF using their presets.

       

       

      Does anyone know what is happening to my PDFs, and how I can export to PDF from InDesign without getting NChannel?

        • 1. Re: NChannel Question from InDesign
          Eugene Tyson Adobe Community Professional & MVP

          Surely this is a gradient made from Cyan, magenta, yellow or black?

           

          I'm thinking the printers workflow is a little bit old. I thought DeviceN or "nchannel" was only a description of a spot colour? It shouldn't cause any issues? I'm wondering why the printers are even checking for this?

          • 2. Re: NChannel Question from InDesign
            Eugene Tyson Adobe Community Professional & MVP

            Since I reckon the printers have an older workflow, I think the nchannel is only with pdf 1.6 or higher.

             

            I think if you made a pdf with 1.5 or even 1.4 (transparency is flattened with 1.4) then it shouldn't show up.

             

            And since I think the printers are using ancient workflows (ancient is such a weird word to use) that I think it's probably best to make this PDF flattened.

             

            Always get colour proofs, especially in situations like this.

            • 3. Re: NChannel Question from InDesign
              Dov Isaacs Adobe Employee

              Exactly what nChannel evidence do you have? Depending upon how you export the PDF, you might end up with content is SeparationBlack. That is effectively equal to CMYK=(0,0,0,k) and should cause no problems with display or any RIP that conforms either to the official PostScript or PDF specifications.

               

                        - Dov

              • 4. Re: NChannel Question from InDesign
                WBTxTx1 Level 1

                I made the PDF using 1.4 and saw the same result. This is a one color (K)  project I am working on. I have attached before and after screenshots/images showing the color of the object in the PDF which I am placing into InDesign, and the after screenshot which shows the NChannel conversion. I have seen the same thing a few times now, and the only common element sems to be that I am placing a PDF into InDesign, and  the element in the PD is gray 0% brightness.

                 

                Before

                Before.jpg

                 

                After

                After.jpg

                • 5. Re: NChannel Question from InDesign
                  Dov Isaacs Adobe Employee

                  Forget PitStop. Use the Acrobat 10 or Acrobat 9 Output Preview Separations and Output Preview Object Inspector functions to see what you really have. If you have content that is SeparationBlack, you are good to go. That is equivalent of CMYK=(0,0,0,k).

                   

                            - Dov

                  • 6. Re: NChannel Question from InDesign
                    WBTxTx1 Level 1

                    I am only up to Acrobat version 8, so I can't use the tool you described. In the preflight report I can see that this only uses one sep (K)

                     

                    I have also found that NChannel show up only when I place a PDF into InDesign when the PDF contains gray. If I place a grayscale .jpg or .tiff for example, the color comes  out exactly the same in the resulting PDF, with no NChannel. The conversion to NChannel only happened using PDFs. I even used PDF optimizer to flatten the PDF first before placing it in InDD, but that had no effect.

                     

                    Why does InDesign convert the color for GS PDFs, and is there a way to make it stop doing that?

                     

                    Colors.jpg

                    • 7. Re: NChannel Question from InDesign
                      Eugene Tyson Adobe Community Professional & MVP

                      It's already been said, stop using Pitstop.

                       

                      Use Acrobats tools to see what's really in the PDF.

                       

                      Perhaps Dov can guide you more on how to troubleshoot this in Acrobat. But Pitstop seems to be the problem here.

                      • 8. Re: NChannel Question from InDesign
                        WBTxTx1 Level 1

                        Ok I found a copy of Acrobat 9. I used the object inspector tool, and here is what is shows.

                         

                        Inspector.jpg

                        • 9. Re: NChannel Question from InDesign
                          Colin Flashman Adobe Community Professional

                          i noticed in the OP's post that the printer's REP is making the comment. what does the printer's ART DEPARTMENT think?

                           

                          i use acrobat 8 and enfocus pitstop 10 to diagnose faults with supplied PDFs at work. It is possible in acrobat 8 to go to the output preview and turn on separations. if the black channel is turned off, what happens? does the page go white (indicating that black was the only colour on the page) or is colour still visible?

                           

                          I've had PDFs in the past with DeviceN as the OP is describing but am outputting to an Apogee X RIP and the art separates on the black channel just fine.

                           

                          as to the mechanics of what's going on when making the PDF... no idea.

                          • 10. Re: NChannel Question from InDesign
                            Dov Isaacs Adobe Employee

                            That should RIP without any problem with the content of that SeparationBlack going to the K channel.

                             

                                      - Dov

                            • 11. Re: NChannel Question from InDesign
                              WBTxTx1 Level 1

                              That is correct. In Acrobat 8 when I go to Output Preview and turn off process black, the page is completely blank.

                               

                              I have also noticed that in InDesign, any objects that have transparency effects such as drop shadows applied to them are NChannel in the resulting PDF. Once again, I see the same result in Acrobat's output preview.

                               

                              The printer will not accept files that contain NChannel because they say "NChannel... does not convert to gray correctly"

                               

                              Looks like this inquiry is goint to  lead me back to the printer for more details.

                              • 12. Re: NChannel Question from InDesign
                                Eugene Tyson Adobe Community Professional & MVP

                                Again, I think the printer is too overly concerned or else working with a very old system. I think this is down to the grayscale images or gradients/continous tones.

                                 

                                I was able to rid the Device N by going to PDF optimiser and I ticked the

                                 

                                Under Discard User Data I have ticked

                                 

                                Discard document info and metadata

                                Discard all object data

                                Discard private data of other applications

                                Discard hidden layer content and flatten visible layers

                                 

                                Under Discard Objects I have ticked


                                Discard embedded print settings

                                 

                                 

                                 

                                I'm not entirely sure which one cause the DeviceN to disappear.

                                 

                                But it didn't come up again after I did that.

                                • 13. Re: NChannel Question from InDesign
                                  WBTxTx1 Level 1

                                  Thank you everyone for your help on this topic. This issue has been resolved. A different printer has confirmed that the N Channel in our files RIPs just fine. As everyone here has said, the issue was not with my files, but with the workflow of the original printer..