write a harris corner detector in matlab

main.m
function [R, L] = harrisCornerDetector(I, k, thresh)

% Convert input image to grayscale
if size(I,3) == 3
    I = rgb2gray(I);
end

% Compute gradient of image
[Ix, Iy] = gradient(double(I));

% Compute products of derivatives for Harris corner measure
Ix2 = Ix.^2;
Iy2 = Iy.^2;
IxIy = Ix.*Iy;

% Compute sums of the products of derivatives at each pixel
Sx2 = conv2(Ix2, ones(3), 'same');
Sy2 = conv2(Iy2, ones(3), 'same');
Sxy = conv2(IxIy, ones(3), 'same');

% Define scale factor and threshold for Harris corner response R
alpha = 0.04;
R = (Sx2.*Sy2 - Sxy.^2) - k*(Sx2 + Sy2).^2;
L = R > thresh*max(R(:));

end
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