8 Replies Latest reply on Jan 12, 2017 7:09 AM by BobLevine

    why white lines on pdf

    Lex Webb

      Hi, I am producing pdfs using the Pass4press profile and am getting thin white lines appearing where there are boxes containing PSDs with transparent backgrounds.

       

      How can I avoid this?

       

      Many thanks

        • 1. Re: why white lines on pdf
          Günter Heißenbüttel Adobe Community Professional

          This issue is normally due to image flattening in combination with antialiasing and quite unavoidable. These lines aren't visible at print output. If you go to Acrobat's preferences and switch off "Page Display/ Smooth line art" and "Smooth images" the lines should disappear, if you look at your PDF in 100% size.

          • 3. Re: why white lines on pdf
            rob day Adobe Community Professional & MVP

            just to clarify, changing your Acrobat Page Display preference has no affect on the actual file and the flattening artifacts are still there.

             

            In general it's best practice keep transparency live unless the printer is using very old equipment—PDF-X-4 is preferred over PDF/X-1a where there will be no stitching because there's no flattening.

            • 4. Re: why white lines on pdf
              Lex Webb Level 1

              Hi Rob, do you mean the white lines will still be there? I'm producing the pdfs using the magazines requested Pass4Press profile via InDesign.... If I use say Sony's profile I can't see them. Should I be adapting the profile? I believe its main job is to reduce ink coverage ....

              • 5. Re: why white lines on pdf
                Agenturaxact Level 1

                it is not normally.... If open this pdf in "new" CC Photoshop have lines.... it is BAD not normally... and sure if same pdf open in OLDs Photoshop e.g. 5.0 raster picture is perfect without lines!!!

                • 6. Re: why white lines on pdf
                  rob day Adobe Community Professional & MVP

                  Hi Rob, do you mean the white lines will still be there?

                   

                  That's right the Page Display preference is only affecting the preview, not the file.

                   

                  When you flatten on export, the page gets cut up into pieces and how that is done is handled by the Transparency Flattener preset you choose under the Export Advanced tab. In general it's safe to say stitching artifacts will not print on a high resolution device assuming the flattener preset choices are appropriate, but they can show on low res devices (monitors & composite printers).

                   

                  The more modern PDF/X-4 workflow delays the handling of transparency to output where the device capabilities are known.

                  • 7. Re: why white lines on pdf
                    rob day Adobe Community Professional & MVP

                    it is not normally.... If open this pdf in "new" CC Photoshop have lines.... it is BAD not normally.

                    When you open a PDF into Photoshop you are "RIPing" the PDF into a bitmap, so you can use Photoshop to show how flattening works.

                     

                    Here I've exported the same page to PDF/X-1a (flattened) and PDF/X-4 (live) at a low res 72ppi. Because of the low res RIP, the X-1a export shows the stitching artifacts, which are not there in the X-4 version:

                     

                    Screen Shot 2017-01-12 at 9.55.42 AM.png

                     

                    If I reimport the X-1a flattened version at the resolution of a typical platemaker (2400ppi) the artifacts are not there because of the resolution:

                     

                    Screen Shot 2017-01-12 at 10.03.27 AM.png

                    • 8. Re: why white lines on pdf
                      BobLevine MVP & Adobe Community Professional

                      I think it's worth mentioning at this point that many publication have not updated their files requirements in many years. I've found a phone call directed at the right person can result in some clarification. Absent that, then use the X1-a setting and design appropriately.