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An analog-to-digital converter (ADC) can be modeled as two processes: sampling and quantization. Sampling converts a time-varying voltage signal into a discrete-time signal, a sequence of real numbers. Quantization replaces each real number with an approximation from a finite set of discrete values.
When analog video is converted to digital video, a different sampling process occurs, this time at the pixel frequency, corresponding to a spatial sampling rate along scan lines. A common pixel sampling rate is: 13.5 MHz – CCIR 601, D1 video; Spatial sampling in the other direction is determined by the spacing of scan lines in the raster. The ...
Discrete cosine waveform with a frequency of 50 Hz and a sampling rate of 1000 samples/sec, efficiently satisfying the sampling theorem for the reconstruction of the original cosine function from samples. (The effects of quantization are too subtle to be seen in this graph.) The process of analog-to-digital conversion produces a digital signal. [6]
Quantization, involved in image processing, is a lossy compression technique achieved by compressing a range of values to a single quantum (discrete) value. When the number of discrete symbols in a given stream is reduced, the stream becomes more compressible.
The term Nyquist Sampling Theorem (capitalized thus) appeared as early as 1959 in a book from his former employer, Bell Labs, [22] and appeared again in 1963, [23] and not capitalized in 1965. [24] It had been called the Shannon Sampling Theorem as early as 1954, [25] but also just the sampling theorem by several other books in the early 1950s.
4-channel stereo multiplexed analog-to-digital converter WM8775SEDS made by Wolfson Microelectronics placed on an X-Fi Fatal1ty Pro sound card AD570 8-bit successive-approximation analog-to-digital converter AD570/AD571 silicon die INTERSIL ICL7107. 3.5 digit (i.e. conversion from analog to a numeric range of 0 to 1999 vs. 3 digit range of 0 to 999, typically used in meters, counters, etc ...
Digital image processing allows the use of much more complex algorithms, and hence, can offer both more sophisticated performance at simple tasks, and the implementation of methods which would be impossible by analogue means. In particular, digital image processing is a concrete application of, and a practical technology based on: Classification
Digital signal processing (DSP) is the use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations. The digital signals processed in this manner are a sequence of numbers that represent samples of a continuous variable in a domain such as time, space ...