15 Replies Latest reply on Dec 10, 2013 12:02 PM by TWsolange

    output for printing (rgb/cmyk related)

    TWsolange Level 1

      Hello,

       

      I've been sending out PDF's in the past with RGB photos onboard. My previous printer company didn't bother (I guess)...maybe they converted themselves to CMYK.

       

      My new printer company says I can only send photos that are in CMYK. They advised me to already change this in Photoshop (as I learned it's also possible when creating the PDF from within indesign).

       

      I've been googling a few weeks around, red a lot about the RGB/CMYK issue and it's all very confusing. I can't seem to find the perfect answer. A lot of articles are contradictory....

      I've also been testing with converting from RGB into CMYK in photoshop, and 90 % of the photo's don't change, but 10 % does...and with those, the difference is realy big....

       

      So now my question :

       

      What is the perfect way to convert from RGB to CMYK before sending out to a printer ? (I use COATED FOGRA 39, which should be the best solution for Europe).

      Shal I convert already in Photoshop, or do I input my photos in RGB into Indesign and convert while creating the PDF ? Is there any difference between the Photoshop conversion or Indesign to PDF conversion?

      Last question : If RGB is not suitable to print, why are all digital photo's automatically in RGB and print fine when creating a photobook ?

       

      THANKS a million in advance for any help on this issue !

       

      Greetz from Luxembourg,

      Solange

        • 1. Re: output for printing (rgb/cmyk related)
          Eugene Tyson Adobe Community Professional & MVP

          The printer you are working with is way behind the times.

           

          The colour conversion should be done at the RIP stage.

           

          Your best PDF to send is a PDF x4a - and you should check with your printer if they even know what this is.

           

           

          There's no need to convert your images from RGB to CMYK in photoshop.

           

          Basically - RGB has a wider gamut that's different to CMYK.

           

          By changing the colour of the photo to CMYK in photoshop - you're going to be left with a CMYK image that if converted back for the web or digital printing to RGB - there is no way to get the same RGB colours again.

           

           

           

          The RGB images need to be converted to CMYK and your printing company should be handling that.

           

          You should also get colour proofs - as your screen doesn't match their printers, so what you see on the screen when you convert RGB to CMYK is not reliable.

          • 2. Re: output for printing (rgb/cmyk related)
            Peter Spier Most Valuable Participant (Moderator)

            If the printer wants CMYK and ahs already said they can't do the conversions, then you don't have a choice other than do as requested or find another printer.

             

            Doing the conversion during export allows you to maintain a single file for multiple output situations, changing the color to the correct profile for each situation. On the other hand, you have less control. The results would be the same as if you opened the photo in Photoshop and simply used the convert to profile command, then saved with no further modification. If you're like me and like to do little adjustments after the color conversion, and don't mind a single-purpose file, converting in Photoshop can give you a bit better results, but that's up to your skills.

             

            In either case, it's vital that you know in advance what the correct CMYK destination profile is for doing the conversion. If this printer doesn't know what you are talking about when you ask for it, you should eriously consider finding a printer who does. Your FOGRA 39 guess could be correct, or it could be wrong and your colors will not reproduce as you expect, and I pretty much guarantee that a printer who deamnds CMYK without giving you the correct profile will say to you "you did the conversion and we printed the colors you gave us" when you complain that the color is wrong.

            • 3. Re: output for printing (rgb/cmyk related)
              Danny Whitehead. Level 4

              My new printer company says I can only send photos that are in CMYK. They advised me to already change this in Photoshop (as I learned it's also possible when creating the PDF from within indesign).

              As Eugene suggested, this is the old fashioned way, and suggests they're somewhat stuck in the 90s. There's absolutely no need to convert in Photoshop. If you're sending CMYK PDFs, the printers wouldn't know whether you'd converted to CMYK in PS or in ID when exporting. If the two applications have their colour settings synced, the conversions will be identical.

               

              It might be worth asking them which CMYK profile they reccomend you convert to, or if they have their own that they can provide you with. I'm not optimistic about the level of expertise their response will suggest, though.

              Last question : If RGB is not suitable to print, why are all digital photo's automatically in RGB and print fine when creating a photobook ?

              RGB is an additive colour model, suited to capturing colours and displaying them on a light-emiting device like a monitor, CMYK is a subtractive colour model, based on four inks that absorb and reflect light rather than emit it. Sorry if that isn't the best explanation - my brain isn't working 100% this afternoon - but a Google search on colour models might be more enlightening! I guess Photo book printers/labs want RGB because they carry a wider range of colours, and they can make the conversion that produces the best results on their equipment.

              • 4. Re: output for printing (rgb/cmyk related)
                TWsolange Level 1

                Thanks for your quick replies !

                 

                So if I understand correctly : I can leave the pictures in RGB (at least when it's photos, the rest such as logos, backgrounds...which  I created in illustrator...I have them in CMYK) and create the PDF x4a.

                I'll talk again to my printer....and unfortunately...I can't choose the printer myself. I'm helping out a fanfare-band with their posters and flyers and they have this printer company :-(

                 

                Thanks !

                solange

                • 5. Re: output for printing (rgb/cmyk related)
                  Eugene Tyson Adobe Community Professional & MVP

                  Well you can do the conversion to CMYK as suggested through InDesign.

                   

                  There's no need to convert in photoshop first.

                   

                  And see if the printing company has PDF Joboptions file - that file will contain all the correct information for their printing press.

                   

                   

                  If not - I have a Coated Fogra pdf joboptions file here - using PDFx1a - and use this profile when dealing with printers that I can't choose.

                   

                   

                  Perhaps you could try this (make sure to ask the printers what bleed amount they require)

                   

                  https://dl.dropboxusercontent.com/u/17210757/Eugenes.joboptions

                   

                  Please only use this at your own discretion - I accept no responsibility for any loss.

                  • 6. Re: output for printing (rgb/cmyk related)
                    Eugene Tyson Adobe Community Professional & MVP

                    Using that pdf joboptions

                     

                    Save it to your computer

                     

                    In InDesign

                     

                    File>Adobe PDF Presets

                     

                    Load

                     

                    And select the file.

                     

                     

                    Then make the PDF using the setting from the dropdown list.

                    • 7. Re: output for printing (rgb/cmyk related)
                      TWsolange Level 1

                      Thanks Eugene,

                       

                      I'll try this but talk to my printer on Monday anyway first ;-)

                       

                      Best regards,

                      Solange

                      • 8. Re: output for printing (rgb/cmyk related)
                        Danny Whitehead. Level 4

                        The colour conversion should be done at the RIP stage.

                        I'm repeating something I wrote in another thread, which I came back to a month or so later with more information, but for some reason it didn't bump back the first page.

                         

                        Anyway... I wanted to move to an X-4 workflow with the RIPs doing the conversions, but found that Fiery RIPs didn't do as good a conversion as the Adobe CMM. After a bit of correspondence with an EFI tech, it turns out the CMMs are different - most importantly the Fiery RIPs don't do Black Point Compensation, so shadow detail is lost. So I'm stuck doing the conversion when I export to PDF.

                        • 9. Re: output for printing (rgb/cmyk related)
                          rob day Adobe Community Professional & MVP

                          You can make the same RGB to CMYK conversion in Photoshop, export, or at output. Whether the conversion happens on export or at output, you have to have an accurate monitor profile and the conversion destintion has to be the correct press profile. Letting the conversion happen at the printer doesn't guarantee anything if either or both of the profiles are wrong.

                          • 10. Re: output for printing (rgb/cmyk related)
                            Eric.White_StrategicHS Level 1

                            I know that RIPs can and should be able to do the conversions...but there is NO WAY I'm sending a job off to a printer (especially a printer I'm not familiar with) and just trusting them to convert my photos and still expecting them to turn our right. No flip'n way.  I've worked on the prepress and and the design end of this and can tell you from experience: unless a printer has invested in the proper equipment they are either going to straight up reject the job (like in this case) or force it through a RIP with a generic color profile which will likely make your photos look flat, muddy or both (stupid tiny CMYK gammut). If you have no idea what profiles or what processes your printer is using...why would you blindly turn over your files over to them and still expect your prints to look right? Yes, there are printers out there that have the right equipment and software...but not all of them and until you KNOW for sure there's no sense in gambling with your work. It doesn't take a whole lot of time on the design end to prepare your files for a CMYK press so take the time to adjust and color correct your photos before sending them.

                            • 11. Re: output for printing (rgb/cmyk related)
                              TWsolange Level 1

                              Thanks all for the replies !

                              I have a meeting with the printer company next week. I'll discuss what he really wants (which format PDF).

                               

                              In the meantime, I have a poster and flyer back that they have printed (where he asked high print quality PDF) and the results are very beautiful. Colours are perfect (actually, the same as I have them in my project).

                              Next project is more difficult (more photos and so more possibility to screw up). So therefore I will go and see him to find out more.

                               

                              Best regards,

                              solange

                              • 12. Re: output for printing (rgb/cmyk related)
                                rob day Adobe Community Professional & MVP

                                but there is NO WAY I'm sending a job off to a printer (especially a printer I'm not familiar with) and just trusting them to convert my photos...

                                It doesn't take a whole lot of time on the design end to prepare your files for a CMYK press so take the time to adjust and color correct your photos before sending them.

                                 

                                Fair enough, but you still have to communicate with the printer to know what the press profile is in order to make the best conversion in PS or on export. If you guess that the default US SWOP is the press profile, but the printer's press is more like US Sheetfed you'll likely be disappointed—the two profiles produce very different CMYK values.

                                • 13. Re: output for printing (rgb/cmyk related)
                                  Eric.White_StrategicHS Level 1

                                  Rob, I completely agree.

                                   

                                  The bottom line for me, I suppose, is that I'm a control freak in that way. I don't trust other people (or machines) to mess with my color.

                                  • 14. Re: output for printing (rgb/cmyk related)
                                    rob day Adobe Community Professional & MVP

                                    I don't trust other people (or machines) to mess with my color.

                                     

                                    I think it's become increasingly difficult to control output values via export.

                                     

                                    One online printer I use tells me their press profile is GRACol and I can send a PDF/X-4 page with the same Adobe RGB or GRACol CMYK image and get the exact same color back—they are really good.

                                     

                                    Another very large online printer tells me to use US SWOP (even for their uncoated?) but all CMYK color gets converted to new CMYK values whether it's profiled or not—they're not so good.

                                    • 15. Re: output for printing (rgb/cmyk related)
                                      TWsolange Level 1

                                      It stays a difficult thing...those color conversion...

                                      I'm not a pro...helping out people now and than...and I adore lay-outing...

                                       

                                      But now I realize that I have to learn a lot about printing-requests as well....

                                       

                                      Is on program now !