Resizing an image to a certain file size

Discussion in 'Digital Photography' started by Thijs Moonen, Mar 5, 2015.

  1. Thijs Moonen macrumors member

    Joined:
    Aug 22, 2011
    #1
    Hi,

    I have a question that seems very simple but might be more complicated.

    There's a series of photographs that I need to resize to a certain file size. The photos are in CMYK and 300 dpi and their native size is around 16 mb.

    So the givens are CMYK, 300 dpi, and a file size of say 1.1 MB. Is there a way that, in Preview.app or Photoshop.app I can ask the program to resize the picture to meet those givens?


    Thanks,
     
  2. Bending Pixels macrumors 65816

    Joined:
    Jul 22, 2010
    #2
    It's easy to do in Photoshop. Go under Image/Image Size and type in the dimensions and resolution you want.
     
  3. bhtwo macrumors 6502a

    bhtwo

    Joined:
    Dec 31, 2012
    Location:
    Oxford UK
    #3
    I think one of those three will have to be a variable... so probably no.

    I'm very likely wrong but i don't think so.
     
  4. dwig macrumors 6502

    Joined:
    Jan 4, 2015
    Location:
    Key West FL
    #4
    You would need to be saving the file in a compressible format (e.g. JPEG, ...) if you want to maintain the same number of pixels (read: same reproduction size in inches at 300 pixels per inch). The full version of Ps running on OSX or Windows would allow you to "Save for Web and Devices..." and in that dialog you can adjust the JPEG compression until it reports that the file will be the size you want.

    With Ps's regular File>Save... function you can also adjust JPEG compression but the dialog doesn't provide the size predictions so it is more a trial-and-terror process of saving, looking at the resulting file size, and resaving again at a different compression... . Also, the Ps File>Save... JPEGs are larger for the same image quality/compression than files created by the File>Save for Web and Devices... function. The latter strips out proprietary Ps data (e.g. guides, certain app settings, ...) that are embedded in the file when using File>Save...
     
  5. Thijs Moonen thread starter macrumors member

    Joined:
    Aug 22, 2011

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