A term meaning Dots Per Inch. This represents the total number of dots in the horizontal and vertical directions that a printer puts onto paper (or the printing substrate). The DPI measurement of a printer often needs to be considerably higher than the pixels per inch measurement of a video display in order to produce similar-quality output. This is due to the limited range of colors for each dot available on a printer. At each dot position, the simplest type of color printer can print a dot consisting of a fixed volume of ink in each of four color channels (CMYK). With various combinations of ink, a printed dot can have one of 8 unique colors. This compares to a computer screen, where each pixel can produce one of 16 million unique colors. In order for a printer to produce variable colors it must use a halftone process. Thus, in effect, it requires a printer 4 to 6 dots to faithfully reproduce the color contained in a single pixel. A 300 PPI image would require a printer DPI setting of 1,800 to be reproduced as it is seen on the screen (300 x 6).