function histogram(file)
image = imread(file);
[rows, cols] = size(image);

histogram = zeros(256);

for i = 1:rows
    for j = 1:cols
        pixel = image(i,j);
        histogram(pixel+1) = histogram(pixel+1)+1;
        
    end
end

maxy = max(histogram);
x = 0:1:255;
plot(x, histogram(x+1));
set(gca,'XLim',[0 255])

end