Digitizing, or digitization, is the process of turning an analog signal into a digital representation of that signal. Analog signals are continuously variable, both in the number of possible values of the signal at a given time as well as in the number of points in the signal in a given period of time. However, digital signals are discrete in both of those respects, and so a digitization can only ever be an approximation of the signal it represents.

A digital signal consists of a sequence of values, each value often represented by a sequence of bits, and each bit often represented by a voltage level. Digitization is performed by reading an analog signal A, and, at regular time intervals (sampling frequency), representing the value of A at that point by a digital value. Each such reading is called a sample.

There are two main factors determining how close an approximation to an analog signal A a digitization D can be. The bit rate of D, formally the number of bits in D per time unit, represents how often A is sampled.

The images we see on the TV screen, the raster display of a computer, or in newspapers are in fact "digitized images".

Digitizing is the primary way of storing images in a form suitable for transmission and computer processing.

See also: Analog to digital converter, raster image, raster graphics, vector graphics, digital audio