Adaptive image contrast enhancement using generalizations of histogram equalization

  • Authors:
  • J. A. Stark

  • Affiliations:
  • Dept. of Eng., Cambridge Univ.

  • Venue:
  • IEEE Transactions on Image Processing
  • Year:
  • 2000

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Abstract

This paper proposes a scheme for adaptive image-contrast enhancement based on a generalization of histogram equalization (HE). HE is a useful technique for improving image contrast, but its effect is too severe for many purposes. However, dramatically different results can be obtained with relatively minor modifications. A concise description of adaptive HE is set out, and this framework is used in a discussion of past suggestions for variations on HE. A key feature of this formalism is a “cumulation function,” which is used to generate a grey level mapping from the local histogram. By choosing alternative forms of cumulation function one can achieve a wide variety of effects. A specific form is proposed. Through the variation of one or two parameters, the resulting process can produce a range of degrees of contrast enhancement, at one extreme leaving the image unchanged, at another yielding full adaptive equalization