4. Image Enhancement

  1. Maria Petrou and
  2. Costas Petrou

Published Online: 27 JAN 2011

DOI: 10.1002/9781119994398.ch4

Image Processing: The Fundamentals, Second Edition

Image Processing: The Fundamentals, Second Edition

How to Cite

Petrou, M. and Petrou, C. (2010) Image Enhancement, in Image Processing: The Fundamentals, Second Edition, John Wiley & Sons, Ltd, Chichester, UK. doi: 10.1002/9781119994398.ch4

Publication History

  1. Published Online: 27 JAN 2011
  2. Published Print: 9 APR 2010

ISBN Information

Print ISBN: 9780470745861

Online ISBN: 9781119994398



  • generic deblurring algorithms;
  • high frequency noise;
  • histogram manipulation;
  • image enhancement;
  • linear filtering;
  • low frequency interference


Image enhancement is the process by which we improve an image so that it looks subjectively better. Manipulation of images often entails omitting or enhancing details of certain spatial frequencies. Noise in images is often assumed to be either impulse noise or Gaussian noise. Low frequency interference arises when the image has been captured under variable illumination. The process of enhancing the high frequencies of an image is called sharpening and it may be achieved by high pass linear filtering. Small image details may also be enhanced by using nonlinear filters based on local image statistics. There are more sophisticated methods, which as well as stretching the range of grey values, allocate a predefined number of pixels at each grey level. These methods are collectively known as histogram manipulation. The chapter discusses generic deblurring algorithms that may be achieve by using mode filtering, mean shift or toboggan enhancement.

Controlled Vocabulary Terms

genetic algorithms; image enhancement; low-frequency noise; nonlinear filters