%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%
%%% This function produces a numerical approximation to 2D Gabor function.
%%% Parameters:
%%% sigma = standard deviation of Gaussian envelope, this in-turn controls the
%%% size of the result (pixels)
%%% orient = orientation of the Gabor clockwise from the vertical (degrees)
%%% wavel = the wavelength of the sin wave (pixels)
%%% phase = the phase of the sin wave (degrees)
%%% aspect = aspect ratio of Gaussian envelope (0 = no "width" to envelope,
%%% 1 = circular symmetric envelope)
%%% pxsize = the size of the filter (optional). If not specified, size is 5*sigma.
%%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function gb=Gabor(sigma,orient,wavel,phase,aspect,pxsize,shift,dispa)
if nargin<6
pxsize=fix(5*sigma);
end
if mod(pxsize,2)~=0
[x, y]=meshgrid(-fix(pxsize/2):fix(pxsize/2),-fix(pxsize/2):fix(pxsize/2));
else
[x, y]=meshgrid(-fix(pxsize/2)+0.5:fix(pxsize/2)-0.5,-fix(pxsize/2)+0.5:fix(pxsize/2)-0.5);
end
x = x+dispa; % add disparity tuing
orient=-orient*pi/180; % rotate subfield
x_theta=x*cos(orient)+y*sin(orient);
y_theta=-x*sin(orient)+y*cos(orient);
phase=phase*pi/180;
freq=2*pi./wavel;
shift_x=shift(1);
shift_y=shift(2);
gb=exp(-0.5.*( (((x_theta+shift_x).^2)/(sigma^2)) ...
+ (((y_theta+shift_y).^2)/((aspect*sigma)^2)) )) ...
.* (cos(freq*y_theta+phase) - cos(phase).*exp(-0.25.*((sigma*freq).^2))); |