Process of conversion of continuous (analog) signals, such as the detected radiation (voltage), into numbers. This is carried out with an analog to digital converter. There are two kinds of discretization involved: the voltage is only measured (sampled) at particular discrete times and only voltages within a particular range and separated by a particular minimum amount can be distinguished. Voltages beyond this range are said to exceed the dynamic range of the digitizer.

The basic unit of information.
Definition: The smallest unit of information in the storage on a computer. Eight bits are grouped together to form one byte, additional start and stop bit.
Larger units are
kilobyte (kB) = 1 000 bytes (computer storage 1024 bytes)
megabyte (MB) = 1 000 kB (computer storage 1024 kB)

See also Bit Range, Binary System, Decimation, Digitization, Sampling Rate and Picture Archiving and Communication System.

Conversion of the analog signal to a series of digital values by measurement at a set of particular times; this utilizes the analog to digital converter. If the rate of sampling is less than twice the highest frequency in the signal, aliasing will occur. The duration of sampling determines how small a difference of frequencies can be separated.

See also Algorithm, Trigonometric Functions, Digitization, Exponential Functions, Imaginary Number, Logarithms, Point Spread Function.