11 Replies Latest reply on Dec 14, 2014 6:29 PM by gener7

    Set photos from 92 DPI to 300 DPI. Valid for printing?

    robby_vww Level 1

      Hi

       

      I've been working on a flyer for a new client and it is almost ready for printing. Just now I discovered that all the photos the client provided are in 92 DPI (dimensions: 4288px x 2848px), which means that they are not fit for printing. (The photos were taken by some photographer a year ago.)

       

      I tried the following solution:

      - I adjusted the DPI of the photos to 300 (Image > Image Size...) ;

      - This automatically changed the dimensions to 11000x9000 (or something);

      - I set the dimensions back to the original size (4288px x 2848px);

      - I saved the photos (new name & folder ofc).

       

      Everything seems to look valid, but I was wondering if somebody has had experience with what I did and if these photos are suitable for (professional) printing after this "conversion".

       

      Tanks in advance!

        • 1. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
          JJMack Most Valuable Participant

          robby_vww wrote:

           

          Hi

           

          I've been working on a flyer for a new client and it is almost ready for printing. Just now I discovered that all the photos the client provided are in 92 DPI (dimensions: 4288px x 2848px), which means that they are not fit for printing. (The photos were taken by some photographer a year ago.)

          That is not a correct statement. What the means is the Image will print poster size something like 46"x30" at a 92DPI resolution. Printing the image that size at that resolution may be quite acceptable depending on the image content and the quality of the pixels.

           

          Changing the print resolution to 300DPI  without resampling will change the print size to 14.2" x 9".5: Change to 356DPI it will print 12" x 8"  these printed image may be suitable for framing depending on image content and quality of pixels.

           

          Not a single pixel will change all print will have the same 12.2Mpixels Only the size of the printed pixels are different.

           

          The human eye can only resolve down to 300dpi cloes up.  You do not view an almost 4' wide image close up large prints are not required to have a high resolution like 300DPI.

           

          People view image with their eves they do not examine an image with a loop to evaluate at what resolution they are printed.

          • 2. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
            robby_vww Level 1

            I'm really sorry, but I don't really understand your answer.

             

            The thing is: when I want to print this through a professional printing company, they want everything in 300 DPI resolution for excellent printing quality. So my conclusion is that the photos I used in my design need to be 300 DPI as well, or am I wrong? (Because this is what the printing company told me.)

             

            However: The original photos are 4288x2848, but in my design, I shrank them to a dimension of 1250x850 or smaller.

            • 3. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
              gener7 Adobe Community Professional & MVP

              4288px x 2848px

               

              What size in inches do you want the print to be on paper?

               

              Gene

              • 4. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
                Warunicorn Adobe Community Professional

                It's fine that they're at 300 DPI. JJ was just trying to tell you that resampling changes the rules. A lot of it depends on the quality of the image being resized/resampled. It's almost always better to resize down than up.

                 

                What JJ said is also true: Printing a poster-sized image at 300 DPI may look better close-up...but who's going to get really close to a wall-sized poster to begin with? It's kind of a waste at that size.

                 

                I'm curious, though: You said you were designing a flyer that the pro printer will print. Why do they need the images in the document to be at 300 DPI? Your document is already at 300 DPI to begin with?

                • 5. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
                  gener7 Adobe Community Professional & MVP

                  He said he changed it to 300 ppi by upsampling, which must really trash the pictures and bloat the file size.

                   

                  He could in Image > Image Size, uncheck "resampling" on the originals and changed the resolution from 92 to 300 ppi to satisfy the printer's requirements and leave the original pixel dimensions untouched.

                   

                  Gene

                  • 6. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
                    JJMack Most Valuable Participant

                    robby_vww wrote:

                     

                    I'm really sorry, but I don't really understand your answer.

                    Then you have a lot to learn. Till you understand the basics of digital image processing you will be able to do image processing well.

                    • 7. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
                      robby_vww Level 1

                      It is a small flyer, 4.1" x 6.5"? I use the metrical system, so not really used to inches. But it's about 1200x2000 pixels.

                       

                      I think I shrank the images at least 3/4 of their original size to fit in my design. My dad has told me a bit more about the resolution and stuff, so I'm fine at the moment, seems that my pictures are big enough to fit in my design and I should not worry about the pictures being 92 DPI. (My design is 300 DPI, to be clear!)

                      • 8. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
                        robby_vww Level 1

                        Warunicorn wrote:

                         

                        It's fine that they're at 300 DPI. JJ was just trying to tell you that resampling changes the rules. A lot of it depends on the quality of the image being resized/resampled. It's almost always better to resize down than up.

                         

                        What JJ said is also true: Printing a poster-sized image at 300 DPI may look better close-up...but who's going to get really close to a wall-sized poster to begin with? It's kind of a waste at that size.

                         

                        I'm curious, though: You said you were designing a flyer that the pro printer will print. Why do they need the images in the document to be at 300 DPI? Your document is already at 300 DPI to begin with?

                        Thanks for the explanation. Figured out something like that, but his formulation was a bit odd.

                         

                        Initially, I had one image of 70 DPI and that image did cause a blurry result in my design, so therefor I addressed them and they said "to get the best result, every photo should be 300 DPI". I already replaced that image, but then I discovered that the others were 92 DPI. But my dad already gave me a suitable reply. My design being 300 DPI and just 1200x2000 pixels, I needed to shrink each photo at least 3/4 of its original size (4288x2848). Thus, being 'just' 92 DPI, these photos would not cause any trouble in my design and in the result of the actual print.

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                        • 9. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
                          robby_vww Level 1

                          gener7 wrote:

                           

                          He said he changed it to 300 ppi by upsampling, which must really trash the pictures and bloat the file size.

                           

                          He could in Image > Image Size, uncheck "resampling" on the originals and changed the resolution from 92 to 300 ppi to satisfy the printer's requirements and leave the original pixel dimensions untouched.

                           

                          Gene

                          Indeed, I did not consider to uncheck the "resampling" box. So I took a look at your suggestion and it seems to work fine. Will be helpful in the future.

                           

                          Thanks for the tip!

                          • 10. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
                            JJMack Most Valuable Participant

                            You need to understand Pixels better.  There are  things you need to be concerned  with  about pixels.

                             

                            On one hand pixel is just some values  that represent a color.

                             

                            A pixel has no size till a resolution is set. DPI resolution defines the size the image will be rendered with.  However All devices used to render images do not support DPI resolution Devices like LCD Displays only support a single DPI resolution.  You may see the term Native resolution.   All Image displayed are displayed at that resolution.  Image processing programs scale image up and down in size to display images to for you.  In Photoshop image window you will see a Zoom percentage displayed in the window bar.  The only time you are actually seeing the images real pixels is when the zoom level is 100% the actual pixels are being displayed.  They are being displayed at the Display Native DPI resolution which most likely is not the resolution  set in the Image Mapping.  In most cases what you see is larger then what would be printed.  To help to visualize what the image would look at Printed Photoshop has and option View Print Size.  If you have set your Displays Native resolution into you Photoshop Preferences Photoshop will scale(zoom) the image to display Print size on your display.   The Image display will be Print size but will be the Displays DPI resolution.

                             

                            Pixels also have some quality.  The quality of all pixels are not the same.    If you have a very good camera with a very good lens it can capture very high quality image pixels.  However that does not mean all pixels from your camera are high quality.  However they are the best pixels you have for the image. Lens Have a depth of field so some pixels will be in focus and sharp other will not. The may other factors like improper Focus, exposure, Camera shake.  Still the pixels are the best ones you have. So some image should be kept and some discarded.

                             

                            When ever you resample interpolate an image you look some image quality.  When you interpolate an image change the number of pixels you have for an image you wine up with a completely new image. Not a single original camera pixel remains.  All Pixels are generated for the original pixels by some computer routine.  No pixels is captured by a device at the place the image was captured.  If you reduce the number of pixels you throughout details you had for the image.   If you increase the number of pixels your adding details that might be correct. Down size images tend to look sharper while up size images tend to look softer.

                             

                            How may pixels does one need to have.?   The Answer is the number of pixels needed to render and acceptable image.   There is no precise answer.   I have written The best pixels you have for your image are the original pixels you get from the source be it your Camera or fro a friend.  Preserve those pixels work from copies.    I do not like to Resample  I only do that when necessary.

                             

                            If you have 18Mpixels and you want to display in in a Web page you have too many pixels you must resize and reduce the number of  pixels so the web size image will fit within the page. Do not save over the original.   When printing you want to print an acceptable image.   If the image is going to be small like a 6"x4" it  need to be printed at a high resolution because people will be looking are it close up.  The human eye can resolve down to 300DPI.  Still that does not mean a image must be 300DPI.  If the number of pixels  you have for the image would need to be printed at 200DPI to get a 6"x4" it may be fine.  If you have a 16Mpixels image like I get from my Canon 1D Mk4  4896x3264px it would print 6"x4" at 816DPI.    I do not resample that to 300dpi there is no need too. If the printer you use can handle it.   My printer is an old Epson 4800 and its maxi mun resolution on high quality photo  paper can easily handle 816DPI my eyes can't but my printer can.

                             

                            Many users seem to feel print must be 300DPI and printers Print at 300DPI best.    The thing is an image DPI and your Printer DPI setting are two different things.   An image having a 300DPI means a pixel is 1/300"x1/300" there are 90,000 per square inch.   Ink jet printers do not print these with a single drop of ink 1/300"x1/300" or even several drops that size. Drops would not be square in the first place.  Inkjet printer use many higher resolution drops of ink to color in the much larger 1/300"x1/300" image pixels areas.  Your printers DPI setting is a quality setting not pixel size the higher settins  print finer high quality pixel but uses more ink.  On Photo Paper I always use my printers 1440 or 2880 DPI setting.

                            • 11. Re: Set photos from 92 DPI to 300 DPI. Valid for printing?
                              gener7 Adobe Community Professional & MVP

                              If I can sum this up, I think it will make things easier for you until you are comfortable with digital imaging basics.

                               

                              You have a file at 4288px x 2848px but the resolution is reported at 92 ppi. The printer wants 300ppi.

                               

                              Maybe you don't want to get into a debate with him and you just want the work done.

                               

                              No problem.

                              You turn off resampling, change 92 to 300 and save. Your pixels are untouched and untainted.

                               

                              When you again look at it in Image Size, it will print at 14.293 x 9.493 in or 36.31 x 24.11 cm at 300 ppi.

                               

                              Maybe your printer won't care and can scale it down to fit your brochure.

                               

                              Maybe he will call you back and ask for 6.5 x 4.1 in @ 300 ppi

                               

                              No problem. Image > Image Size  Check the Resample box. Type in 6.5 inches. It will be 6.5 x 4.3 to preserve the aspect ratio.

                               

                              Click OK. The final size is 6.5 x 4.3 at 300 ppi. Pixel dimensions are 1950 x 1295 px.  You've lost pixels but the density is still 300.

                              Of course you do a Save As... and rename it to keep your original file untouched.

                               

                              Image > Duplicate is a good command to learn if you want to keep your original and down sample the copy to job specs.

                               

                              Tiff or PSD, whatever the printer wants. Avoid lossy files formats like jpegs.

                               

                              Gene