| function G = createGabor(or, n) | |
| % | |
| % G = createGabor(numberOfOrientationsPerScale, n); | |
| % | |
| % Precomputes filter transfer functions. All computations are done on the | |
| % Fourier domain. | |
| % | |
| % If you call this function without output arguments it will show the | |
| % tiling of the Fourier domain. | |
| % | |
| % Input | |
| % numberOfOrientationsPerScale = vector that contains the number of | |
| % orientations at each scale (from HF to BF) | |
| % n = imagesize (square images) | |
| % | |
| % output | |
| % G = transfer functions for a jet of gabor filters | |
| Nscales = length(or); | |
| Nfilters = sum(or) | |
| l=0; | |
| for i=1:Nscales | |
| for j=1:or(i) | |
| l=l+1; | |
| param(l,:)=[.35 .3/(1.85^(i-1)) 16*or(i)^2/32^2 pi/(or(i))*(j-1)]; | |
| end | |
| end | |
| % Frequencies: | |
| [fx, fy] = meshgrid(-n/2:n/2-1); | |
| fr = fftshift(sqrt(fx.^2+fy.^2)); | |
| t = fftshift(angle(fx+sqrt(-1)*fy)); | |
| % Transfer functions: | |
| G=zeros([n n Nfilters]); | |
| for i=1:Nfilters | |
| par=param(i,:); | |
| tr=t+param(i,4); | |
| tr=tr+2*pi*(tr<-pi)-2*pi*(tr>pi); | |
| G(:,:,i)=exp(-10*param(i,1)*(fr/n/param(i,2)-1).^2-2*param(i,3)*pi*tr.^2); | |
| end | |
| if nargout == 0 | |
| figure | |
| for i=1:Nfilters | |
| max(max(G(:,:,i))) | |
| contour(fftshift(G(:,:,i)),[1 .7 .6],'r'); | |
| hold on | |
| drawnow | |
| end | |
| axis('on') | |
| axis('square') | |
| axis('ij') | |
| end | |