[YeGoblynQueenne]

I think I understand what you meant by heuristics. I agree that it's impractical to try and hand-code image recognition rules and all attempts to do that in the past have failed as they have in similarly complex domains (like machine translation, say). My concern is particularly about the use of neural networks (or in general machine learning models that learn to approximate a function) in domains where precision is normally required, like engineering. I mean, I know there's plenty of approximation in engineering already but of course we're not talking about computing integrals here (er, I think?).

Anyway I was especially trying to understand the OP's comment about speedup using a neural network. I'm still a bit confused about that. But thanks for the conversation.