Gray Level Co-occurrence Matrix in Octave

glcm.m

function Y=glcm(X, dx, dy, grayScale)
% (dx, dy):
%   ( 1, 0)   0°
%   ( 0, 1)  45°
%   ( 1, 1)  90°
%   (-1, 1) 135°

[m, n] = size(X);
maxGrayScale = max(X) + 1;
X = floor(X.*grayScale./maxGrayScale);
Y = zeros(grayScale,grayScale);
for i = 1:m-dy
    for j = 1:n-dx;
        r = X(i,j)+1;
        c = X(i+dy, j+dx)+1;
        Y(r,c) = Y(r,c)+1;
    end
end
Y = Y./(m*n);

end