% SPATIALGABOR - applies single oriented gabor filter to an image % % Usage: % [Eim, Oim, Aim] = spatialgabor(im, wavelength, angle, kx, ky, showfilter) % % Arguments: % im - Image to be processed. % wavelength - Wavelength in pixels of Gabor filter to construct % angle - Angle of filter in degrees. An angle of 0 gives a % filter that responds to vertical features. % kx, ky - Scale factors specifying the filter sigma relative % to the wavelength of the filter. This is done so % that the shapes of the filters are invariant to the % scale. kx controls the sigma in the x direction % which is along the filter, and hence controls the % bandwidth of the filter. ky controls the sigma % across the filter and hence controls the % orientational selectivity of the filter. A value of % 0.5 for both kx and ky is a good starting point. % showfilter - An optional flag 0/1. When set an image of the % even filter is displayed for inspection. % % Returns: % Eim - Result from filtering with the even (cosine) Gabor filter % Oim - Result from filtering with the odd (sine) Gabor filter % Aim - Amplitude image = sqrt(Eim.^2 + Oim.^2) % % Peter Kovesi % School of Computer Science & Software Engineering % The University of Western Australia % pk at csse uwa edu au % http://www.csse.uwa.edu.au/~pk % % October 2006 function [Eim, Oim, Aim] = spatialgabor(im, wavelength, angle, kx, ky, showfilter) if nargin == 5 showfilter = 0; end im = double(im); [rows, cols] = size(im); newim = zeros(rows,cols); % Construct even and odd Gabor filters sigmax = wavelength*kx; sigmay = wavelength*ky; sze = round(3*max(sigmax,sigmay)); [x,y] = meshgrid(-sze:sze); evenFilter = exp(-(x.^2/sigmax^2 + y.^2/sigmay^2)/2)... .*cos(2*pi*(1/wavelength)*x); oddFilter = exp(-(x.^2/sigmax^2 + y.^2/sigmay^2)/2)... .*sin(2*pi*(1/wavelength)*x); evenFilter = imrotate(evenFilter, angle, 'bilinear'); oddFilter = imrotate(oddFilter, angle, 'bilinear'); % Do the filtering Eim = filter2(evenFilter,im); % Even filter result Oim = filter2(oddFilter,im); % Odd filter result Aim = sqrt(Eim.^2 + Oim.^2); % Amplitude if showfilter % Display filter for inspection figure(1), imshow(evenFilter,[]); title('filter'); end