terminology - What does DPI mean?

What does DPI mean and how does it affect images displayed on screen versus printed?

Answer

DPI, or Dots Per Inch relates to the dot density when printing.

To help better understand the relationship of DPI to pixel dimensions, take an 800x600 pixel image for example:

• Using 300dpi, an 800x600 image will print 2.6x2 inches.


• Using 200dpi, an 800x600 image will print 4x3 inches.



• Using 100dpi, an 800x600 image will print at 8x6 inches.

Notes:

• As the DPI gets less dense, or lower, the print quality degrades.


• The pixel dimensions don't change in the example, only the printed pixel density


• Extremely large prints may be printed at lower DPI because they are viewed at a distance


• When changing DPI in a photo editing program, you can choose to resample which will change pixel dimension, or, if you choose not to resample, the pixels remain unchanged, only the print dimensions change.