[xfs]

Folds are not complicated. They are just not familiar to the intended readers.

The changed version is idiomatic in image processing or similar areas that deal with pixels. Being idiomatic makes it familiar to read, and easy to change.

[hhmc]

But the wider context here -- and the reason the changed version was presumably written -- is the accusation that folds are overcomplicated.

It's under that lens that I am criticizing the changed code.

[sharpneli]

Not just folds. Also the lambda and the inner loop which is memcpy instead of range3. It’s about every part of the function, including but not limited to the folds.