[versteegen]

Not really propriety software - as you & bildung said, it's not a problem if you can just buy a license. I meant anyone working on FLOSS software that isn't GPL compatible, which is probably most FLOSS software. MIT, BSD, etc are very popular these days. And image formats are generally intended to be widely-adopted standards used across different applications.

[yarrel]

Most "FLOSS" software is GPL. Almost all is GPL compatible.

But even the FSF recommend sometimes using don't-care-about-user-freedom licenses for strategic reasons, for example driving adoption of a new free codec...