Resolution

File resolution

When you scan an image, you must give it a resolution that stays with the file, regardless of which monitor or output resolution used to view it.

All Web graphics must be 72 dpi. Scan at 150 dpi and then reduce the resolution (Image-->Image Size) to 72.

Monitor resolution

This refers to the dots per inch displayed on your computer monitor. Most Macintosh monitors default to 72 dpi --dots per inch-- while most Windows monitors use 96 dpi. In theory, if you took a ruler and held it up to your Mac's monitor, you could count 72 dots for every inch across your screen.

Output resolution

Printers also have their own resolutions that determine how many dots they print within each inch on the page. The more dots per inch a printer uses, the smoother the gradations appear within your printed page.