12 Replies Latest reply on Feb 13, 2012 3:30 AM by Eugene Tyson

    Large 72 ppi to small 300ppi for magazine? CS4

    Paul R Stark Level 1

      I have a jpeg file that is roughly 44" x 33" (3200 x 2400 pixels) at 72 ppi. Will it work for print if I downsize it to 6" x 4" (1800 x 1200 pixels) and upsample it to 300 ppi?

       

      Thx.

       

      Paul

        • 1. Re: Large 72 ppi to small 300ppi for magazine? CS4
          BobLevine MVP & Adobe Community Professional

          That’s roughly 11x8 at 300ppi

           

           

           

          Bob

          • 2. Re: Large 72 ppi to small 300ppi for magazine? CS4
            Paul R Stark Level 1

            In other words, if I don't adjust the document size, especially proportionally, I can upsample to 300 ppi that will be suitable for print or must I also resize?

             

            Also, what is the formula that got you to 11 x 8 @ 300 dpi?

             

            Thx.

             

            Paul

            • 3. Re: Large 72 ppi to small 300ppi for magazine? CS4
              BobLevine MVP & Adobe Community Professional

              Pretty simple math.

               

              3200/300 is pretty damn close to 11. 2400/300 is exactly 8.

               

              You just rescale the image in InDesign and work with that. I wouldn't even bother with Photoshop to be honest with you unless this was going to be some serious high end coffee table book.

               

              Bob

              • 4. Re: Large 72 ppi to small 300ppi for magazine? CS4
                Paul R Stark Level 1

                So you would scale a 72 ppi photo in ID to fit the frame (about 6x4, slanted) and that would have the same effect as upsampling and resizing in PS and then send it to the printer? This isn’t a high end coffee table book. It’s a color curriculum workbook, but I do want it to look good.

                 

                Also, although new to this Adobe product, everything I’ve read strains to insist that images be 300 ppi and don’t change the proportions.

                 

                Image resolution

                 

                ·         IMPORTANT: For high quality printing results, image file resolution should be saved at approximately 300 dpi (dots per inch) at 100% of the image's final output size.

                ·         For sufficient printing resolution, digital images should have a resolution of 300 ppi (pixels per inch).

                Taken from http://inkd.com/earn/graphics-basics.

                 

                By the way, just for the record, upsampling a 72 ppi jpeg photo in PS or rescaling it in ID will achieve 300 ppi or is this not a true 300 ppi? If rescaled in ID, you have no concerns about the quality of the final printed material in a magazine, for example?

                 

                Thx.

                 

                Paul

                • 5. Re: Large 72 ppi to small 300ppi for magazine? CS4
                  Peter Spier Most Valuable Participant (Moderator)

                  Paul,

                   

                  When you say "upsample" most of us will presume you mean you are going to artificially increase the resolution of the image in Photoshop by checking the "Resample Image" box in the Image Size dialog. If that box is UNCHECKED, when you change the dimensions your resolution will also cahnge, in inverse proportion to the scaling.

                   

                  There is nothing "magic" abpit an image and its resolution. Look at the pixel count, divide that by the number of inches you've chosen to save as teh image dimension, and you have the resolution at that size. Changing the dimensions (scaling) without resampling does not alter the pixels, so the resolution changes automatically. If you make the image 50% smaller, you double the resolution. It makes no difference if you do it in Photoshop or ID, other than it will affect how large the image is displayed at any given scale value (i.e. your image at 100% is currently 44 x 33, but if you change the dimensions in Photoshop to 10.67 x 8 without resampling, the resolution will cahnge from 72 ppi to 300 ppi, and when you place the file in ID at 100% if will shrink to 10.67 x 8, which might actually fit on your page). the only other differnce will be in the size of the preview image that is stored in the ID file. A 72 ppi image will store essentially the entire image as a preview, but a high resolution image will save a 72 ppi downsampled preview. This will have no effect on output.

                   

                  >

                  Will it work for print if I downsize it to 6" x 4" (1800 x 1200 pixels) and upsample it to 300 ppi?

                   

                  This actually would be downsampling, not upsampling, in this case, since at those dimensions the current image would have a resolution of about 600 ppi. Downsampling is generally OK. You may lose some detail whether you downsample or just scale as the printing is only going to use as much data as required to make the image and will ignore the excess.

                  • 6. Re: Large 72 ppi to small 300ppi for magazine? CS4
                    Paul R Stark Level 1

                    OK, I think I get it. But I was doing it all wrong. I thought resampling increased or decreased the ppi in PS when checked (on). I was resizing (proportionally), changing the resolution manually to 300 ppi, but with resampling checked. That's not really doing anything to the image, if I understand correctly, or does that have the same effect?

                     

                    If I uncheck Resample Image in PS, and resize the document to 6 x 4.5 (remaining proportional), I get a resolution of 533.333. Then, if I need to downscale it somewhat in ID, this will in fact increase the resolution even more, if I understand correctly. If this is true, when the workbook is printed, won't I have images with potentially numerous different resolutions? Is this okay or will it be obvious that some images look incredible and others look more like mediocre?

                     

                    Finally, if I've got this all correct, I can use jpeg's in my project, scale them to fit the frame in ID (as long as they end up around 300 ppi or just manage it with precision in PS to be sure), and just make sure I export to PDF using CMYK. Sound good?

                     

                    Thx.

                     

                    Paul

                    • 7. Re: Large 72 ppi to small 300ppi for magazine? CS4
                      Peter Spier Most Valuable Participant (Moderator)

                      When the resample box is checked, Photoshop is either going to throw away or add more pixels unless the new dimensions happen to coincidentally match the chosen resolution. Enter your new dimensions, then watch waht happens to the pixel count and file size in the top of the dialog when you uncheck and then check the resample box and enter a new number into the resolution field.

                       

                      It's OK to have multiple resolutions in the file. Most of the export Presets will do some downsampling for overly large images anyway, and you've already said this isn't fine art. As I said before, too much image data isn't going to help or make the image print any better, it just slows down the processing in the RIP. Most of us here will tell you that if you have good quality jpegs you cn go right ahead and place them, but we would not resave as jpeg again if you need to do any editing. Instead we'd use TIFF or PSD, both lossless formats, rather than doing any more degradation of the image. Max Quality jpeg is OK for a few rounds, but every save operation degrades a jpeg a little bit more becaue it is a lossy format.

                      • 8. Re: Large 72 ppi to small 300ppi for magazine? CS4
                        Paul R Stark Level 1

                        Okay, so this is more than one way "to skin a cat". Manually changing resolution to 300 ppi with resampling and then manually changing the document size to 10.667 x 8 has the exact same effect as unchecking resampling and changing the document size to 10.667 x 8.

                         

                        I'm taking my jpeg's into PS and saving as PSD's precisely because it's lossless. The great thing I learned today was that if I have a sufficiently large jpeg at 72 ppi, I can make it a 300 ppi PSD and use it. THANKS FOR THAT!

                         

                        Paul

                        • 9. Re: Large 72 ppi to small 300ppi for magazine? CS4
                          Bo LeBeau Level 4

                          One of great things in InDesign is the ability to see both the Actual PPI and Effective PPI for scaled images.

                           

                          If you open the Links panel or the Info panel you can see these, The Effect PPI is the important number for print purposes.

                           

                          In the example you can see the image was 72 ppi when placed in InDesign, but it was scaled down to 22.6% which raised the Effective PPI to 318 ppi.

                           

                          (Click the image in the forum to see an enlarged view)

                           

                          effective-ppi.jpg

                          1 person found this helpful
                          • 10. Re: Large 72 ppi to small 300ppi for magazine? CS4
                            Paul R Stark Level 1

                            Now that was helpful. Thx. I was placing 300 ppi images--just checked one--682 effective ppi after scaling. Crazy when I only need 300 ppi for print.

                             

                            Thanks again.

                             

                            Paul

                            • 11. Re: Large 72 ppi to small 300ppi for magazine? CS4
                              BobLevine MVP & Adobe Community Professional

                              When you export the PDF (surely you aren’t thinking of sending native files) you can choose whatever number you want.

                               

                               

                               

                              Bob

                              • 12. Re: Large 72 ppi to small 300ppi for magazine? CS4
                                Eugene Tyson Adobe Community Professional & MVP

                                If your original image is 72 ppi

                                 

                                Place it in InDesign at full size.

                                 

                                In the Control Panel (the strip that runs across the top) there's a place to insert percentage.

                                 

                                Insert 24%

                                 

                                72 ppi /24*100 = 300ppi