Pixels per inch, a measurement of pixel density, depends on the resolution of a document or device. The average PPI is about 72 dots per inch. The input resolution can be measured by pixels per inch (PPI), and a good photograph usually requires 300 DPI.
PPI and DPI can be used in reference to printing images on paper, computer monitor and TV resolutions, as well as digital cameras (which have three dots per pixel) and smartphone screens. The proper amount of PPI will be determined by the size of the image. Pixels per inch also can be interchanged with pixels per centimeter (PPCM), as they are both measurements of pixel density.