tic
fprintf("loading\n");
img = imread("/Volumes/home/GSVitec/GREEN/GREEN_F4.0_25ms/144554.tiff");
toc
RGB = zeros(img.width/2, img.height/2, 3, "uint8");

for y = 1: img.height/2
    for x = 1:img.width/2
        % on odd rows, the matrix goes BGBGBGBGBGB....
        if mod(y, 2) == 1
            % on odd pixels, the pixel is a blue pixel
            if mod(x, 2) == 1
                RGB(x, y, 3) == img(x, y);
            end
        end
        
    end
end
