[edflsafoiewq]

The first two extensions (constrained deflate, multithreaded encoding/decoding) only present optimization opportunities for the decoder. It is still the same image.

Single-threaded decoding of large PNGs is enough of a bottleneck that Apple has their own version of PNG with multithreading support.

[layer8]

It’s also not really a different format then, just a constrained form of PNG.