Neurosciences and ophtalmology


From Oct 15th 2003 to Nov 15th 2004, I was a post doc fellow at Steve Shevell's Visual science lab , in the University of Chicago , Chicago, IL - USA.

My  research interests inluded temporal nulling of chromatic induction, LMS cones sensitivity, receptive field response according to spatial/temporal modulation, as well as the retinal image computation

In the above figure, the test circles seems to have different chromaticities (viewed some distance away from the screen ~ 1 meter).

The left one appears orange, whereas the right one appears more pink.

They are physically identical, but due to the response of a cortical center / surround spatially antagonistic receptive field, the test ring's neighborhood induces this change in color appareance.

Chromatic assimilation and contrast both act to induce this different color perception.

You don't believe me ? Just step closer to the screen, and check out by yourself ! (at a viewing distance of a few inches)

  Purple-Lime concentric rings  Lime-Purple concentric rings    


During my post-doc position, I've been working working on the effects of a temporal nulling of such chromatic induction.

See my Poster a the European Conference on Visual Perception (ECVP)

A pretty big part of my post-doc researchs focused on the computation of retinal images.

These works are based on Larry Thibos's works on the computation of the Point Spread Function.

The convolution of the point spread functions by the wavelength decomposition of the displayed images provides the wavelength retinal images.

The weighting summation of the wavelength retinal images and the Smith-Pokorny fundamentals gives the L, M & S cones absorption.

The figure below summarizes the different steps of the retinal image computation.

Retinal image computation

Check out here for further details on the software and its different steps.

I hope I will soon be able to provide some source code and images here !