8 Replies Latest reply on Feb 9, 2012 5:45 PM by Noel Carboni

    Inches vs. Pixels in Photoshop vs. InDesign


      I'm confused.


      I told InDesign to make my page size 600 pixels by 800 pixels. I then changed the ruler to show inches. It showed the page size as 8.333" x 11.111".


      Then I told Photoshop to create a canvas size 600 pixels by 800 pixels. When I changed the ruler to show inches it told me the page size was 2" x 2.667".


      Why the difference? And if I want to create something that is 600 pixels by 800 pixels, which do I believe? I am creating an epub and want a cover that is 600px x 800px - I can create in either INDD or Photoshop, but don't feel confident that it will be the proper size.


      BTW, I'm using CS5 for both products.


      Thx for your help,


        • 1. Re: Inches vs. Pixels in Photoshop vs. InDesign
          Rik Ramsay Level 4

          It's all to do with the resolution - dpi. By those figures, your InD file is on web setup with 72 dpi (roughly) but your PSD file is at 300dpi. Make the PSD resolution same as your InD and they should match up.

          • 2. Re: Inches vs. Pixels in Photoshop vs. InDesign
            Noel Carboni Level 8

            I have no idea about InDesign, but in Photoshop when you made your new image you were asked how many pixels/inch to set in the metadata.  That's why it's reporting 2" x 2.667".


            It's all arbitrary, for use when doing things that require physical output such as printing.


            If I recall correctly, the ppi value in the File - New dialog is just the value you used last time, or maybe it's the value from the last image you edited...  I'm not completely sure.  There's a setting in Edit - Preferences - Units & Rulers for expressing your preferences, but I hardly ever see that value used.



            • 3. Re: Inches vs. Pixels in Photoshop vs. InDesign
              Trevor.Dennis Adobe Community Professional

              Noel, I used to have Type size set as cm in Preferences because I know the physical print size of a document, so would have a better idea of how text will appear on the screen.  Then I saw a tutorial that recommended setting Type to pixels for the same reason, so I dutifully followed this advice.  I wished I hadn't and I shall be going back to cm in preferences, because pixels just doesn't mean anything.


              DPI is a useful way of adjusting grid size.  If you open the Image size dialogue window, turn off resize, and change dpi to something like 300 or greater, then the grid size becomes easier to view and use IME.   I have both Print and Screen resolution set to 300 for this reason.  (I don't own Illustrator, so do all of my design work in Photoshop using grids and guides.)

              • 4. Re: Inches vs. Pixels in Photoshop vs. InDesign
                Noel Carboni Level 8

                I guess it has to do with how you think.  I think in pixels, with the physical unit data being arbitrary metadata that facilitates additional operations, and that seems to keep me out of trouble. 


                I can't imagine an advantage to setting the screen resolution to anything but the accurate ppi value of your monitor.



                • 5. Re: Inches vs. Pixels in Photoshop vs. InDesign
                  craig cheatham Level 1

                  The reason you would set the file resolution to anything other than your monitor's resolution is that in the long ago bye bye, before the interwebs, but after stone tools, there was something called PRINT. It was a poor, analogue medium that required participation of the consumer, what you might now call interfacing. For instance, the user would have to HOLD the printed object and move it toward and away from his face. Instead of clicking, the user would have to employ his opposable thumb and and a finger to grab a PAGE and turn it to the next one.


                  Images were PRINTED in PRINT and  were composed of HALFTONE DOTS. How many DOTS PER INCH could determine how many shades of gray could be represented, and gray could have color substituted. Overlaying 4 of these grids of colored dots could create a crude color image. It turns out that in the way back, at the peak of this archaic technology, a grid might be able to put 170 Dots Per Inch, or more, on a PAGE. While still crude in modern terms, this pleased the people of that day.


                  As the light of digital technology dawned, old tech and new overlapped a bit. So, for a while, it became a standard, out of laziness mostly, that 300 PIXELS PER INCH was the sweet spot to create most HALFTONE GRIDS. If a "Graphic Designer" wanted a pretty picture with sharp lines printed in a "magazine" with a HALFTONE GRID at 150 Dots Per Inch, making a Raster Image of 300 pixels per inch worked just fine. So for many of us Neandethals still allowed to live in this modern age, many of us hold on to comfortable old things from Days-Of-Yore, such as knowing exactly what resolution works optimally for which dot pitch so our work that gets PRINTED works well. We still enjoy complaining to a PRINTER (a person with ink in their blood) about the CYAN plate drifting out of registration over the course of a print run. Then we go off the Renaisance Faire.



                  • 6. Re: Inches vs. Pixels in Photoshop vs. InDesign
                    Noel Carboni Level 8

                    Thanks for the info, but I think you misunderstood me.


                    There are two fields in the dialog being discussed:  Print and Screen resolution:





                    • 7. Re: Inches vs. Pixels in Photoshop vs. InDesign
                      craig cheatham Level 1

                      I can't think of a reason to be concerned with the Screen Resolution setting at all.

                      My screen is at 1920x1200. I don't where it would make a difference.

                      • 8. Re: Inches vs. Pixels in Photoshop vs. InDesign
                        Noel Carboni Level 8

                        Well, to be fair I already said that setting is only indirectly involved with making new images, but if you set it accurately then things like your [Print Size] zoom button actually work right.