The human eye and the equipment chain (1/4) Introduction Number of pixels becomes a marketing instrument in the sense that more is better. To evaluate what makes actually sense the final reproduction mode of a photo has to be considered. Maximal useful resolution is given by the human eye and of the applied equipment chain. The human eye on different reproduction modes The human eye capability is given with the limitation to differentiate two points not nearer than about 1 arc minute (1/60 grad) from each other. This leads approximate to 300 dots / inch (dpi) for an A4 format (29,7x21.0cm) with a viewing distance from 25 cm. The 300 dpi resolution has established as a fine printing standard to achieve highest picture quality. Such a picture has 11.8 dots per mm what results in about 3500x2500 dots on the A4 format with totally about 9Mpixels.