Dots Per Inch
Published by marco on
The basic gist is that when you store a graphic in Photoshop, it asks for the Pixels per Inch for the graphic. If this graphic will never be printed or does not need to retain its crispness when printed, this number does not matter at all. With an increasing amount of content created exclusively for the web, the DPI (dots per inch) doesn’t matter at all. The graphic is stored with a certain number of pixels and those dimensions are used when rendering to screen.
Most references recommend storing graphics at 72 DPI, but that is merely because most graphic work is (or was) done on Macintoshes and that is the native DPI of the Macintosh. However, Windows uses 96 DPI as a default. On either system, though, if you actually measure a 72-pixel graphic, it will not be 1 inch long. The physical size will vary, depending on the monitor size and resolution.