Gabor filtering augmented with surround inhibition for improved contour detection by texture suppression

N Petkov, M B Wieling (Institute of Mathematics and Computing Science, University of Groningen, Postbus 800, 9700 AV Groningen, Netherlands; email: petkov@cs.rug.nl; website: http://www.cs.rug.nl/~petkov )

Gabor functions are adequate models of simple cell receptive fields [Daugman, 1985 J. Opt. Soc. Am. A 2 1160-1169] [Jones and Palmer, 1987 J. Neurophysiology 58  1233-1258]. Gabor-energy filters have been used to model complex cells [Morrone and Burr, 1988 Proc. Royal Society London B 235 221-245]. Such filters augmented with non-classical receptive field inhibition [Nothdurft et al, 1999 Visual Neuroscience 16 15-34] were demonstrated to mimic various perceptual effects [Petkov and Westenberg, 2003 Biological Cybernetics 88 236-246]. Furthermore, they substantially outperform previously known contour detection algorithms [Grigorescu et al, 2003 IEEE Transactions on Image Processing 12 729-739]. Nowadays Gabor filters are widely used in various scientific fields: visual perception, computational neuroscience, image processing and computer vision.

We implemented the Gabor filter augmented with surround inhibition and made it available on internet [http://www.cs.rug.nl/~imaging] for use by other researchers. Users can choose form the image material available on the site or upload their own images. The following parameters can be selected: preferred wavelenght; preferred orientation; phase offset; aspect ratio; bandwidth; number of orientations; half-wave rectification threshold; superposition of results for different phase offsets; type, strength and area of surround inhibition; post-processing. The site includes a number of visual perception examples.