Resizing JPG files without losing quality

Discussion in 'Technical Corner' started by Sac Arrow, Oct 13, 2016.

  1. Sac Arrow

    Sac Arrow Touchdown! Greaser!

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    I have a 22x17 inch jpg image, at 150 dpi resolution that I want to turn in to an 8x6 image, at a better resolution (300+ dpi). Is there a way to do this?
     
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  2. John221us

    John221us En-Route

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    Photoshop Elements will do it. I can resize it for you, if you want to email it to me.
     
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  3. bluesideup

    bluesideup Pre-Flight

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    Hi.
    Try IrfanView, free, do the DPI first then the Size.
     
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  4. Sac Arrow

    Sac Arrow Touchdown! Greaser!

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    Thanks John, I might take you up on that, but it may not be necessary. It's a cover graphic (you have seen it) which will go in to a print version, but I think the full size version will work out fine so far.
     
  5. John221us

    John221us En-Route

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    Cool, Let me know.
     
  6. mfisher

    mfisher Pre-Flight

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    I use mogrify

    http://www.imagemagick.org/script/mogrify.php

    Free and very powerful. You can process multiple files at once with just a few keystrokes.

    Just make sure to back up your images before you invoke the command in case you screw up and overwrite your images.
     
  7. kgruber

    kgruber En-Route

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  8. RotorDude

    RotorDude Pattern Altitude

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    Gimp would be happy to do it (my favorite).
     
  9. Dana

    Dana Pre-takeoff checklist

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    You shouldn't need to do anything to the image file itself. It will be scaled at the time of printing (or inserting into another document if that's what you're doing), and it will simply end up at whatever dpi it scales to.

    The image is defined as its pixel size, so 22x17 at 150dpi is 3300x2550 pixels. Dots per inch (DPI) is only used when printing or displaying on the screen. But 22x17 is a different aspect ratio than 8x6, so if you want 8" wide it will be 412.5dpi but it would be 6.18" high so some of the picture would be cropped, or if you want it 6" high it will be 425dip only 7.76" wide.
     
  10. Dana

    Dana Pre-takeoff checklist

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    You shouldn't need to do anything to the image file itself. It will be scaled at the time of printing (or inserting into another document if that's what you're doing), and it will simply end up at whatever dpi it scales to.

    The image is defined as its pixel size, so 22x17 at 150dpi is 3300x2550 pixels. Dots per inch (DPI) is only used when printing or displaying on the screen. But 22x17 is a different aspect ratio than 8x6, so if you want 8" wide it will be 412.5dpi but it would be 6.18" high so some of the picture would be cropped, or if you want it 6" high it will be 425dip only 7.76" wide.
     
  11. Sac Arrow

    Sac Arrow Touchdown! Greaser!

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    And that is precisely how it turned out. The raw image feed stock was 72 dpi, and I worked my template size around that. The printed covers came out quite nice.