Densitometer, device that measures the density, or the degree of darkening, of a photographic film or plate by recording photometrically its transparency (fraction of incident light transmitted). In visual methods, two beams of equal intensity are used.

How does a densitometer work?

A densitometer does not measure color but measures density. In print work, density is caused by the light-stopping ability of the pigments in the printing ink that are deposited on the paper by the printing process. ... The light striking the photodiode is converted into electric energy.

What can a densitometer measure report?

A densitometer is a device that measures the degree of darkness (the optical density) of a photographic or semitransparent material or of a reflecting surface. The densitometer is basically a light source aimed at a photoelectric cell.