image = zeros(500*2, 500*9, 3);
for i = 1:18
    row = ceil(i/9);
    col = mod(i-1, 9)+1;
    image((row-1)*500+1:row*500, (col-1)*500+1:col*500, :) = double(imread(sprintf('%d.png', i)));
end
imwrite(uint8(image), 'mcmaster.png');