Gabor filter

Generates Gabor filters using bandwidth, aspect ratio, phase, wavelength and angle as parameters.

#5237 implements a Gabor filter for image processing. From the comments and through my own use, the implementation seems to have limited freedom, and also the variances are defined in the original x,y instead of the rotated x', y' directions.

The code is a modified version based on http://en.wikipedia.org/wiki/Gabor_filter following the conventions and parameters used in http://matlabserver.cs.rug.nl/edgedetectionweb/web/edgedetection_params.html.

The function accepts scalar inputs only, and each call generates one filter. The filter generated is always real. Should you wish to build a complex Gabor filter, you may use (0 phase) + j(pi/2 phase). Filtering can be performed using conv2( ) or imfilter( ).

An example file is included, which mimics the behavior of http://matlabserver.cs.rug.nl/edgedetectionweb/web/index.html at default settings with Lena.jpg image as input. Note that the scaling of numbers is different from the web-app, but consistent with the formulae in http://matlabserver.cs.rug.nl/edgedetectionweb/web/edgedetection_params.html

Update 18-Nov-2010: Thanks to Rachel (see comment below), I have corrected a mistake in the example file. The results are unchanged though. Also, the cs.rug.nl website seems offline.