-- negative (from a gluas sample)



local x, y, r, g, b

for y = 0, height - 1 do

  for x = 0, width - 1 do

    r, g, b = get_rgb(x, y)

    r = 1 - r

    g = 1 - g

    b = 1 - b

    set_rgb(x, y, r, g, b)

  end

  progress(y / height)

end



