Nope, I asked @caeugusmao to change to the way you described (`img.convert('RGBA').getchannel('A').getextrema()`) since it will be a lot faster. What I said is that, in your first solution, `sum` would have to iterate over all pixels, wouldn't it? And that probably is slower than iterating over in C, at least for large images.    Once again, the last solution you gave is way better. I wasn't aware of `getextrema`.