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Explain digital image sampling and quantization.
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An image may be continuous w.r.t x and y co-ordinate and also in amplitude. To convert it to digital form, we have to sample the function in both co-ordinate and amplitude.

Sampling :

  • The process of digitizing the co-ordinate values is called Sampling.
  • A continuous image f(x, y) is normally approximated by equally spaced samples arranged in the form of a NxM array where each elements of the array is a discrete quantity.

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  • The sampling rate of digitizer determines the spatial resolution of digitized image.
  • Finer the sampling (i.e. increasing M and N), the better the approximation of continuous image function f(x, y).

Quantization :

  • The process of digitizing the amplitude values is called Quantization.
  • Magnitude of sampled image is expressed as the digital values in Image processing.
  • No of quantization levels should be high enough for human perception of the fine details in the image.
  • Most digital IP devices uses quantization into k equal intervals.
  • If b-bits are used,

No. of quantization levels = k = $2^b$

  • 8 bits/pixels are used commonly.
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