Digitizing
From Free net encyclopedia
Digitizing, or digitization, is the process of turning an analog signal into a digital representation of that signal. The term is often used for the scanning of analog photos and video into computers for editing. Since the advent of digital video the term continues to be frequently used, as of 2005, to refer to the process of importing footage into a computer via a FireWire cable. But this is not technically accurate, as the footage is already digital, so it is not really being digitized, but rather encoded into whatever format the non-linear video editing software uses.
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. But the digital representation does not necessarily lose information since the analog signal usually contains both information and noise.
A digital signal consists of a sequence of integers, each integer often represented by a binary number. 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 an integer. Each such reading is called a sample.
A series of integers is not an approximation to an analog signal. However, a series of integers can be transformed into an analog signal that approximates the original analog signal. Such a transformation is called DA conversion. There are two factors determining how close such an approximation to an analog signal A a digitization D can be, namely the sampling rate and the number of bits used to represent the integers.
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.
The term digitizing is also used to describe the process of making a digital representation of features within a raster image using a geographic information system.