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Thread: DPI

  1. #1

    Default DPI

    was wondering, take for eg the exif for one of my images:

    dimensions: 4272 x 2848
    size: 5.2mb
    DPI: 72dpi

    in fact, all my images are only 72dpi.

    I understand for most prints and publications, they require at least 300dpi
    I also understand i can change the dpi through photoshop..

    but i wanna ask, what is the relation between dpi and resolution?

    and why is my camera only producing images of 72dpi? fyi, my cam is a A700 12.2mp

    i did a brief search on the web, but couldnt understand much.. hope a fellow CSer could explain in more layman terms..

    You Need Some Madness In Life To Stay Sane

  2. #2
    Join Date
    Mar 2008

    Default Re: DPI

    correct me if i'm wrong. you're probably referring to ppi here, or pixels per inch.

    you can understand it literally. 72ppi means 72 x 72 pixels of digital image information is used in a printout of 1 square inch. for example, your 4272 x 2848 image at 72 ppi will print at (4272/72) inches by (2848/72) inches. by basic math, if you had the same amount of image data and you chose to print it at 300 ppi, the actual printout will be smaller, i.e. 4272/300 inches by 2848/300 inches

    how much ppi your camera produces is insignificant. 4272 x 2848 @ 72 ppi and 4272 x 2848 @ 300 ppi contain the same amount of data, i.e. 4272 x 2848 pixels. it is only when you're concerned with printing it out that the ppi comes to play, because ppi is essentially the conversion factor between the digital pixels and the actual inches you see on paper.

    that's really my layman understanding, hope it helps


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