How many pixels a scanner can see. Most commonly, this is measured in dots per inch (dpi).For example, a typical flatbed scanner will use a scanning head with 300 sensors per inch, so it can sample 300 dots per inch (dpi) in one direction. To scan in the other direction, it will move the scanning head along the page, stopping 300 times per inch, so it can scan 300 dpi in the other direction as well. This scanner would have an optical resolution of 300 x 300 dpi. Some manufacturers stop the scanning head more frequently as it moves down the page, so their machines have resolutions of 300 x 600 dpi or 300x1200 dpi.
300 x 300 DPI