Applying Derived Gaussian Filters

gistfile1.matlab

% Convert an image to double for increased precision
img = double(img);
    
% Find two derived gaussians with respect to x and y
[hx, hy] = gradient(fspecial('gaussian',[5 5],sigma));

% Run the filters over the image, generating a filtered image
% Leaves x and y images of edges
gx = double(imfilter(img,hx,'replicate', 'conv'));
gy = double(imfilter(img,hy,'replicate', 'conv'));

% Take the absolute value, and combine the x and y edges
mag = sqrt((gx .* gx) + (gy .* gy));

% Use non-maxima suppression 
[mag, ] = max(mag, [], 3);