function setPixel(x, y, pix)

  if x >= 0 and y >= 0 and x < w and y < h then

    pixels[y*w+x+1] = pix

  end

end

-- copy image

w, h = img.width, img.height

pixels = {}

for y = 0, h-1 do

  for x = 0, w-1 do

    pixels[y*w+x+1] = img.getInt(x, y)

  end

end

-- iterate over heatmap

_, _, map = string.find(result, ": (.*)")

for y = 0, h-1 do

  b = math.floor((string.byte(map, y+1)-string.byte("A"))*255/25+0.5)

  for x = 0, 3 do

    setPixel(x, y, b*0x010101)

    setPixel(w-1-x, y, b*0x010101)

  end

end