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JeffreyW
JeffreyW
Known Participant
January 31, 2020
Answered

How to reduce image size for prints

  • January 31, 2020
  • 2 replies
  • 4858 views

I have a JPG that is 20"x30" and would like to print the picture in 12"x18", 10"x15", and 8"x12".

Do I simply go to Image --> Image Size and set the width/height and then export the picture to be printed?

Thx

    This topic has been closed for replies.
    Correct answer D Fosse

    You could do that, but know what you're doing first.

     

    Photoshop doesn't work with physical sizes, that's not a property of the file. Photoshop only works with pixels. Pixels don't have size, they are just data points. The pixel dimensions is the file.

     

    Size is set arbitrarily later. Any image can be printed at any size. The bigger you print, the lower the pixel density - as you can imagine. The pixel density is expressed as pixels per inch, ppi. It means exactly what it says.

     

    You don't want the pixel density to drop too low, then you get poor quality. So there's a limit to how big you can print, depending on the pixel dimensions of the file.

     

    What I'm getting at is this: If you use the Image Size dialog, make sure the "resample" box is unchecked. You don't want to change the number of pixels! This is important.

     

    Of course, if you make copies of your original file, you can do whatever you want with those. But don't resample the original.

    2 replies

    JJMack
    Community Expert
    JJMackCommunity Expert
    Community Expert
    January 31, 2020

    Yes un-check resample then set the width or height you want to print. Photoshop will set the correct print resolution and other side length.  All that happens is the size pixels are printed with changes.  That what Print resolution ppi is. Physical pixels size. All prints will have the same pixels and colors. The one difference is the size pixels are printed. You print different size 3:2 aspect ratio images with the same pixels.

     

    20"x30", 12"x18", 10"x15", and 8"x12" have the same 2:3 Aspect Ratio.

     

    Changing Aspect Ratio would require cropping, distortion's, or boarders.

    JJMack
      JeffreyW
      JeffreyWAuthor
      Known Participant
      January 31, 2020

      TYVM for the verification

      D Fosse
      Community Expert
      D FosseCommunity ExpertCorrect answer
      Community Expert
      January 31, 2020

      You could do that, but know what you're doing first.

       

      Photoshop doesn't work with physical sizes, that's not a property of the file. Photoshop only works with pixels. Pixels don't have size, they are just data points. The pixel dimensions is the file.

       

      Size is set arbitrarily later. Any image can be printed at any size. The bigger you print, the lower the pixel density - as you can imagine. The pixel density is expressed as pixels per inch, ppi. It means exactly what it says.

       

      You don't want the pixel density to drop too low, then you get poor quality. So there's a limit to how big you can print, depending on the pixel dimensions of the file.

       

      What I'm getting at is this: If you use the Image Size dialog, make sure the "resample" box is unchecked. You don't want to change the number of pixels! This is important.

       

      Of course, if you make copies of your original file, you can do whatever you want with those. But don't resample the original.

        JeffreyW
        JeffreyWAuthor
        Known Participant
        January 31, 2020

        TYVM for the reply and information as that was informative.

         

        So to print at a lower ratio like 12"x18" I would want to first make a copy of my picture and them set the size accordingly making sure to uncheck the "resample" box to perserve quality,

         

        I am trying to avoid any clipping when printing at a smaller ratio with my 20"x30" picture as I don't believe a majority of printing services will autoscale the picture for me.

         

        Thx again

        D Fosse
        Community Expert
        D FosseCommunity Expert
        Community Expert
        January 31, 2020

        As long as it's a copy, not the original, you can do whatever you want, including resample. I just needed to prevent any resampling of the original. People will do that, we just had a case two days ago with someone who accidentally destroyed his original by resampling and had to rebuild it.

         

        There are instances where resampling to make a print copy is an advantage. For one thing, you can sharpen the image optimally. This should always be done at final print size and resolution. But you don't have to do it. You can just uncheck the resample box and set the new print dimensions. This will increase the pixel density, and so the ppi number goes up.

         

        The important thing here is that your original is sacred. Always keep that as your master file, and make copies as needed.

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