Dots per inch (dpi) is a characteristic value for the graphic resolution ofprinters, monitors, digital cameras, film scanners, scanners, photoplotters and fax machines and describes the number of pixels per unit length inch, which is 2.54 cm. The higher the dpi value, the better the resolution of the image.
For the metric length system, the inch unit of length must be converted to centimeters or millimeters. Thus, 300 dpi corresponds to 118 pixels per centimeter (ppcm). For example, scanning a 36 x 24 mm slide at a resolution of 4,000 dpi produces a pixel count of over 21 million.
The characteristic value dots per inch (dpi) is used synonymously with pixels per inch( ppi), which should actually be used for the resolution of displays. The dots per inch (dpi) value can be used to directly infer the dot pitch. Thus, a display with a resolution of 300 dpi has a dot pitch of 0.085 mm.