Postgraduate Research Project (DPHIL) School of Life Sciences
*Project Title: Image spectra in the aquatic environment: the consequences of spectrally absorbing media for colour vision and visual communication. *
*Supervisor: Dr Daniel Osorio email
**d.Osorio@sussex. ac.uk*
* *
*Funding: EPSRC January 07 start / BBSRC October 07 start*
*Project Abstract:
*Amongst land animals it is well known that colour is important for object recognition. Colour signals are robust under variations in illumination and context, and so are useful for identifying material properties. Colour constancy is refers to the ability to recognize object colour independent of illumination and is associated with a range of physiological mechanisms. Some of my own work has dealt with problems of colour constancy in natural images, and the demands placed on low-level visual mechanisms.
We know that colour vision is also important for marine animals. Many have multiple types of spectral photoreceptor and they often use colour for communication in courtship displays and many other contexts. Recently there has been intense interest in the role of colour in mating preferences of African Great-lake Cichlid fish, as colour preferences are thought to have had a major role in their explosive speciation.
However colour constancy in water is a problem, because water is a spectrally selective filter. In air, to a good first approximation, the spectrum of light reaching the eye depends upon the reflectance of the object and the illumination spectrum. In water the illumination spectrum varies strongly with depth, and with water quality, and the spectral distribution of reflected light is further modified between the object and the viewer. I have published one paper on the topic in Vision Research.
My present impression is that a number of workers are aware of these issues but that no one is doing serious work in the area.
The D.Phil. student would consider the following questions:
1. What is the problem?
2. How well might various strategies/mechanis ms of colour constancy work in water? This would include consideration of Horizontal cells in fish retina, which have long been known to have complex spectral properties, and are almost certain to play a role
in colour constancy;
3. What are the consequences for visual communication, especially amongst colourful fish. For example what colours should they use and how should the display ? or view displays.
The student would:
1. Develop MATLAB (or similar) models, to answer these questions.
2. Collect spectra and natural image data, on which to run the models.
3. It is possible, but not essential that they would collaborate on or do behavioural work in fish to test predictions of these models.
For further information please contact:
Karen White
Graduate School Co-ordinator, School of Life Sciences,
University of Sussex, Falmer, Brighton BN1 8QG, UK
Email pglifesci@sussex. ac.uk Tel 01273 872774
Postgraduate Information and Prospectus http://www.sussex. ac.uk/pgstudy
Electronic and paper application forms
http://www.sussex. ac.uk/Units/ publications/ pgrad2007/ applynow
[sursa beasiswa]
