What do you understand by Sampling and Quantization with respect to Digital Image Processing? How will you convert an Analog image into a Digital image?

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written 9.5 years ago by

teamques10 ★ 70k

Sampling and quantization are the two important processes used to convert continuous analog image into digital image.
Image sampling refers to discretization of spatial coordinates whereas quantization refers to discretization of gray level values. Normally, the sampling and quantization deals with integer values.
The basic idea behind sampling and quantization is illustrated is illustrated in figure given below: Let F(x,y) denotes an input picture that we want to convert to digital form. Here F represents the brightness at spatial coordinates x and y. An input image may be continuous with respect to the x and y coordinates and also in amplitude. To convert it to digital form we have to sample the function in both coordinates and in amplitude. Digitizing the coordinate values is called sampling. Digitizing the amplitude values is called quantization.

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Every sampled pixel value is quantized to the nearest brightness levels. Total number of brightness levels depends on the number of bit locations used for storage of pixel values.
For example for 2 bit pixel values total number of brightness levels : $2^3$=8 Similarly for 8 bit pixel total number of brightness levels: $2^8$=256.

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