From: Lewis Griffin <[log in to unmask]>

Date: 22 November 2010 07:55:27 GMT

To: [log in to unmask]

Subject: this week's vision@UCL seminar - Thursday, 5pm - Hannah Smithson - Dynamic Colours

Thursday, 25th November, 5pm
Location: MPEB 1.02

Hannah Smithson

Department of Psychology and Biophysical Sciences Institute

Durham University

Dynamic Colours: Perception of Lights, Surfaces and Illuminants t

hat change

The relationship between the trichromatic cone signal and the perception of colour is not straightforward. Many of the mechanisms that support colour perception differ in their latency or in the time-scale over which they operate. I will present psychophysical experiments that have used time-varying stimuli to reveal different colour processing mechanisms. The first experiments use clockwise (CW) and counterclockwise (CCW) modulations around a circular locus in the isoluminant plane of colour space. At 10Hz, these modulations appear different, despite providing sinusoidal modulations to the cones and opponent mechanisms that are matched in their relative amplitudes. We use these stimuli to infer the adaptation characteristics of central colour channels. The next experiments track changes in colour appearance after an abrupt change in simulated illumination. Perceptual adjustments to the new conditions of illumination are slow and delayed, and the dynamics of adjustment depend on spatial parameters of the stimuli. The perception of lights, surfaces and illuminants that change imposes important constraints on models of colour processing.

Hope to see you there.


Lewis Griffin

Senior Lecturer
Computer Science
University College London, UK

http://sites.google.com/site/lewisdgriffin/