Perceptual Systems Faculty
Duane Albrecht (Emeritus)
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LAWRENCE CORMACK
Associate Professor
Two eyes are better than one. The fact that primates and most predators have two frontally placed eyes allows them to determine the relative three-dimensional positions of objects with a remarkable degree of precision. This ability (stereopsis) is not well understood. Research in our laboratory involves: a) psychophysical studies on human observers, b) comparison of these results with models of optimal performance ("ideal observers") and c) computational modeling of the results in order to uncover the computational strategies and specific algorithms used by the human visual system to obtain stereopsis. Currently, we are trying to clearly demarcate the various processing stages involved in stereopsis based on computational arguments, and developing psychophysical tasks to selectively target these stages of processing.
Long-term goals include, but are not limited to, integrating algorithms for stereopsis with a biologically plausible monocular "front-end," integrating or reconciling models of binocular contrast summation with models of stereopsis, and comparing the sensory processes underlying stereopsis with those underlying vergence eye movements.
The laboratory is Macintosh- and PC-based. Special-purpose hardware includes Cambridge Research Systems video display equipped with 12-bit DACs and high-speed LCD binocular shutters, and an SRI dual-purkinje binocular eye tracker with binocular X-Y stimulus deflectors. Experiments are run using software that is developed here (mostly in "C"). Data analysis and modeling are done with a combination of in-house and third-party software.
Courses
Selected Publications
Liu, Y., Bovik, A.C. & Cormack, L.K. (in press) Disparity Statistics in Natural Scenes. Journal of Vision
Kirson D, Huk, AC, Cormack LK (in press) Quantitative characterization of human visual area boundaries using a bootstrapping procedure. Journal of Vision.
Jackson, R. E. & Cormack, L. K. (in press - available online). Evolved navigation theory and the environmental vertical illusion. Evolution and Human Behavior.
I. van der Linde, U. Rajashekar, A.C. Bovik & L.K. Cormack, (in press) DOVES: A database of visual eye movements. Spatial Vision.
Rokers B, Cormack LK, Huk, AC (2008) Strong percepts of motion through depth without strong percepts of position in depth. Journal of Vision, 8(4):1-10
Woodlee MT, Kane JR, Chang J, Cormack LK, Schallert T (2008) Enhanced function in the good forelimb of hemi-parkinson rats: Compensatory adaptation for contralateral postural instability? Experimental Neurology, 211(2):511-7
U. Rajashekar, I. van der Linde, , A.C. Bovik & L.K. Cormack, (2008) GAFFE: A Gaze-Attentive Fixation Finding Engine, IEEE Transactions on Image Processing VOL. 17, NO. 4.
A. Tavassoli, I. van der Linde, , A.C. Bovik & L.K. Cormack, (2007) Orientation anisotropies in visual search revealed by noise. Journal of Vision. Vol 7, Number 12, Pages 1-8
Umesh Rajashekar, Ian van der Linde; Alan C. Bovik; Lawrence K. Cormack (2007) Foveated Analysis of Image Features at Fixations. Vision Research. 41: 3160-3172
Jackson, R. E. & Cormack, L. K. (2007). Evolved navigation theory and the descent illusion. Perception & Psychophysics. Vol. 69, Number 3, Pages 353-362
A. Tavassoli, I. van der Linde, , A.C. Bovik & L.K. Cormack, (2007) An Efficient Technique for Revealing Visual Search Strategies with Classification Images, Perception & Psychophysics Vol. 69, Number 1, Pages 103-112
U. Rajashekar, T. Arnow, A.C. Bovik, and L. K. Cormack (2006) Gaze-centric image analysis for efficient visual search. SPIE Newsroom. [Online]. Available: http://newsroom.spie.org/x3117.xml?highlight=x533
Rajashekar U.,. Bovik, A.C. & Cormack, L.K (2006) Visual search in noise: Revealing the influence of structural cues by gaze-contingent classification image analysis. Journal of Vision Volume 6, Number 4, Article 7, Pages 379-386
Cormack, L. K. (2005) Mathematical models of human vision. In A. C. Bovik (Ed.), Handbook of Image and Video Processing. Second Edition. Academic Press: New York.
H. R. Sheikh, A. C. Bovik, and L. K. Cormack, (2005) No-Reference Quality Assessment using Natural Scene Statistics: JPEG2000. IEEE Transactions on Image Processing.
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