|
Digitizing or digitization〔Also known as digitising or digitisation, digitalizing or digitalization; see American and British English spelling differences. NB not digitalising or digitalisation ((thefreedictionary.com ))〕 is the representation of an object, image, sound, document or signal (usually an analog signal) by generating a series of numbers that describe a discrete set of its points or samples. The result is called ''digital representation'' or, more specifically, a ''digital image'', for the object, and ''digital form'', for the signal. In modern practice, the digitized data is in the form of binary numbers, which facilitate computer processing and other operations, but strictly speaking, digitizing simply means the conversion of analog source material into a numerical format; the decimal or any other number system can be used instead. Digitization is of crucial importance to data processing, storage and transmission, because it "allows information of all kinds in all formats to be carried with the same efficiency and also intermingled".〔McQuail, D (2000) McQuail's Mass Communication Theory (4th edition), Sage, London, pp. 16-34〕 Unlike analog data, which typically suffers some loss of quality each time it is copied or transmitted, digital data can, in theory, be propagated indefinitely with absolutely no degradation. == Process == The term digitization is often used when diverse forms of information, such as text, sound, image or voice, are converted into a single binary code. Digital information exists as one of two digits, either 0 or 1. These are known as bits (a contraction of ''binary digits'') and the sequences of 0s and 1s that constitute information are called bytes.〔Flew, Terry. 2008. New Media An Introduction. South Melbourne. 3rd Edition. South Melbourne: Oxford University Press.〕 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 – generally a finite sequence of integers – therefore a digitization can, in practical terms, only ever be an approximation of the signal it represents. Digitization occurs in two parts: ;Discretization: The reading of an analog signal ''A'', and, at regular time intervals (frequency), sampling the value of the signal at the point. Each such reading is called a ''sample'' and may be considered to have infinite precision at this stage; ;Quantization: Samples are rounded to a fixed set of numbers (such as integers), a process known as quantization. In general, these can occur at the same time, though they are conceptually distinct. A series of digital integers can be transformed into an analog output that approximates the original analog signal. Such a transformation is called a DA conversion. The sampling rate and the number of bits used to represent the integers combine to determine how close such an approximation to the analog signal a digitization will be. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Digitizing」の詳細全文を読む スポンサード リンク
|