3 Replies Latest reply on Apr 20, 2016 6:02 AM by rob day

    InDesign converts RGB-image to CMYK when transparent object is present

    LasseThid

      We just printed a broschure where on one spread the customer had placed an RGB greyscale image that covered both pages. On one of the pages they had placed a white logo and set transparency for the logo to 50%.

      When you export a pdf with no color conversion and include formatted source profiles the page containing the transparent logo the image is converted to CMYK, but the other page remains as RGB. Of course the CMYK  conversion done by InDesign doesn't match the conversion done by the rip, so the two pages looked very different when we printed them.

        • 1. Re: InDesign converts RGB-image to CMYK when transparent object is present
          Willi Adelberger Most Valuable Participant

          To retain transparency and color space you should export as PDF/X-4, a PDF without flattening.

          I suppose the PDF export was similiar to PDF/X-3 as X-3 allows RGB and CMYK in the same file. If an object with transparency is above another object the color space of the upper objects wins. Non affected objects are do not change the color space.

           

          With grey scale image I strongly recommend to use GREY images or CMYK with K only used.

          If you would have exported to PDF/X-1a everything would have change to CMYK.

           

          There is also a problem, objects with vectors are handled different when it comes to flattening than pixel objects. If you have a logo, I think you should a vector file, best AI or PDF/X-4.

          • 2. Re: InDesign converts RGB-image to CMYK when transparent object is present
            Peter Spier Most Valuable Participant (Moderator)

            If you have only RGB images with transparency you could change the blend space from Document CMYK to Document RGB.

            • 3. Re: InDesign converts RGB-image to CMYK when transparent object is present
              rob day Adobe Community Professional & MVP

              the page containing the transparent logo the image is converted to CMYK

               

              How are you determining that the image has been converted to CMYK? Have you checked its space with AcrobatPro's Object Inspector? I'm not seeing a conversion when I export to either PDF/X-4 or High Quality Print—both keep transparency live and object color unchanged. Here I've exported a page with transparency to PDF/X-4, with the blend space as CMYK. You can see the image remains as AdobeRGB.

               

              Screen Shot 2016-04-20 at 8.53.54 AM.png

               

              The ID document's blend space is sent with the PDF, so as Peter suggests, you might want to try RGB. It may be that your RIP is handling the color conversion differently because of the blend space.