It's great to see tables comparing the different approaches, but it's also a bit discouraging to think that you might have to solve the problem a dozen differen

It's great to see tables comparing the different approaches, but it's also a bit discouraging to think that you might have to solve the problem a dozen different ways. Fortunately, it does seem that naive vectorization, for lack of a better term, is pretty effective. For grayscale, "vector floats SSE2" and "vector floats AVX2" aren't far behind the winner. Similarly, for dot product, I might call it a day after AvxDpPs dropped my time from 193 to 34.