Colour image processing

This page describes research work carried out by, or under the supervision of, Dr Steve Sangwine. The research started in about 1992 at the University of Reading, and included the completion of three PhD degrees by students supervised by Steve. Since January 2001, ongoing work in this area has moved to the University of Essex where Steve Sangwine is now a member of the Multimedia Architectures and Applications Research Group in the Department of Electronic Systems Engineering. (One of Steve's former research students remains at Reading.)

The research on colour image processing described here has concentrated on natural colour - that is images derived from a colour camera designed to render scenes for human viewing (such as an RGB camera). The main interest is in digital processing, with an emphasis on theoretical developments in linear filtering of colour images, especially using transforms.


  1. General publications
  2. Hypercomplex colour image processing
  3. Research student projects
  4. Publicly available spin off

General publications

Steve edited (with Robin Horne at Reading) the following book, which is now available from Kluwer, following their acquisition of Chapman and Hall.

Sangwine, S. J. and Horne, R. E. N. (eds.),
The Colour Image Processing Handbook,
Chapman and Hall, March 1998,
ISBN 0-412-80620-7, xvi + 440pp.
See also a tutorial paper on colour:

Sangwine, S. J., 'Colour in Image Processing',
Electronics & Communication Engineering Journal,
12, (5), October 2000, 211-219.

Hypercomplex image processing

A major research interest within the general field of colour image processing, is the use of quaternion, or hypercomplex, numbers for linear processing of colour images. This work is described on its own page.

Research student projects

  1. Anthony Bardos
  2. Dr William Berriss
  3. Dr Amy Thornton
  4. Dr Alan Pritchard

Anthony Bardos (Research student at Reading, part-time, 1995-2002)

Anthony has been studying non-linear vector filtering of colour images. There are details on his own personal page at Reading. Four conference papers have been presented on this work.

Dr William Berriss (Research student at Reading, 1995-2000)

William's research was concerned with analysis of skin wound images with the aim of providing objective analysis of healing status. The abstract (HTML) and full text (gzip compressed Postscript - 6.5MB) of Will's thesis is available from his personal website.

Dr Amy Thornton (Research student at Reading, 1993-1996)

Supported by a University of Reading Research Endowment Trust Fund studentship.

Amy made use of a complex number pixel representation and studied the generalization of monochrome frequency domain methods of object location to colour images, including phase correlation and cepstrum techniques. Amy has now set up her own consultancy, Thornbird Consultancy Ltd. and her thesis is available from her consultancy website.

Dr A.J. Pritchard (Research Student at Reading, 1991-1994)

Supported by an SERC/EPSRC research studentship 1991-1994 Award reference 91700725.

Alan's project was concerned with object recognition using colour attributes. He developed an image recognition system starting with a calibrated RGB image and ending with the desired objects located and their corners defined. His processing makes use of a new rational arithmetic representation for hue. His corner finding algorithm is also new.

Publicly available spin off

This section contains links to material arising from the above work which is publicly available.
Compiled and edited by Dr Steve Sangwine
Last updated: 16 May 2009

To: Department of Electronic Systems Engineering

Valid W3C HTML 4.0!