In imaging and color, the perceived darkness of a substance, material, or image caused by the absorption or reflection of light impinging on the material. Differences in density as related to color are also known as gray levels. As the density of a material increases, the amount of light that is absorbed by the material increases, while the amount of light reflected from or transmitted by the material decreases. The absorption of light is inversely proportional to the transmission or reflectance of light, according to the formula
Density = log101/Transmittance = log101/Reflectance
The term density also refers to the degree of blackness or darkness possessed by a type character, or to the number of characters per unit of line length.
The term density is also used to refer to the storage capacity of a magnetic storage medium, such as a floppy disk, referring to the amount of data that can be stored in a given surface area or per linear track of the magnetic material. It also refers to the number of tracks the particular disk contains.