Understanding the Appearance of Small Spot Colours

David H. Brainard
Collaborators: H. Hofer, D. R. Williams

CRS were once again proud to support the Colour Group at their Vision Meeting at the Institute of Ophthalmology, UCL, London on Thursday 12th January 2006. This year the Cambridge Research Systems Invited Lecture, Understanding the Appearance of Small Spot Colours, was given by Professor David Brainard of the Department of Psychology, University of Pennsylvania, Philadelphia.

Click here to listen to the talk

Click the image above to view the sildes, and listen to Professor Brainard's talk, which was recorded live at the Colour Group meeting. The talk is about 40 minutes long. This presentation has been converted into a Flash file and uses streaming technology, so that you can start watching without waiting for the entire file to download. The presentation will open in a new window and run from start to end automatically, or you can use the controls in the bottom right corner to pause and navigate from slide to slide if you prefer. Don't forget to turn on your speakers!

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Abstract

Hofer et al. (Journal of Vision, vol. 5, no. 5, 2005) report that observers provide a wide range of color names in response to very small monochromatic spots. Here “very small” means spots with a retinal size comparable to that of a single cone (achieved through the use of adaptive optics), and “wide range” includes the term white. In this talk, I argue that a Bayesian calculation designed to estimate the L-, M-, and S-cone signals that were present in the stimulus predicts qualitative features of Hofer et al.’s data. In particular, the calculation predicts that the fraction of spots named white should depend systematically on the arrangement of L-, M-, and S-cones in individual observers’ retinae, in a manner consistent with the experimental data. The calculation combines the (noisy) responses of every cone in the mosaic with prior information about the spatio-chromatic statistics of natural images. It is implemented for actual measurements of the mosaic arrangement of the 5 individual observers of Hofer et al. and for simulations of the small spot presentations through the adaptive optics apparatus.

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