Comment by jiggawatts

Sure, but Apple doesn't fully support HEIC either.

They support only a very specific subset of it, in a particular combination.

Some Apple apps can open third-party HEIC-in-HEIF files, and even display the image correctly, but if you try anything more "complex", it'll start failing. Simply forwarding the image to someone else will result in thumbnails looking weirdly corrupted, brightness shifting, etc...

I've even seen outright crashes, hangs, visible memory corruption, etc...

I bet there's at least one exploitable security vulnerability in this code!