Image Size, Pixels, Resolution and DPI: What’s the Difference?

Posted by · December 6, 2013 11:17 am

accepted solutionA lot of the solutions you see on Experts Exchange deal with highly technical information like creating PHP CHOWN scripts or fixing SQL statements; but almost just as often, novice technology users ask questions for their own educational purposes—and come away learning more than they expected.

Such was the case with the question asked by sheana11: What is the difference between image size, pixels, resolution and dpi?

Web development Sage padas chimed in with an explanation: “The size refers to the physical print size of the image, the resolution is the vertical and horizontal size in pixels and the dpi refers to how many dots fill up the space. If you scan in an 8 X 10 at 300 dpi you end up with a resolution of  2400 X 3000 and that image will be over 20meg.  If you scan the same image that remains at 8 X 10 but this time change your settings to 72 dpi, the resolution will be 576 X 720 and the file size will be just over a meg.”

Sheana11 responded to padas answer by asking if an image could be converted to 72 dpi and 350 x 250 in Photoshop and where to adjust the size, pixels, dots per inch and resolution in Photoshop.

Padas chimed in yet again, answering sheana11’s questions and providing further information about the difference between size, pixels, dots per inch and resolution, prompting this response from sheana11:

“Thank you, Padas, for your detailed explanation and help. Your answer is the reason I’m a member of Experts-Exchange! Thanks again.”

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