First of all, as many others have pointed out by specifying the accepted file formats in the <input> tag, they would avoid HEIC entirely as the phone would simply convert to one of the accepted formats.
It's also not clear to me that this patent license is actually an issue in terms of decoding and converting file formats on the backend. Even if that were the case, I'm certain there is some commercial license software they could purchase to do that for them. This isn't an open-source endeavor, and they charge each student to take the exam.
It's also not clear to me that this patent license is actually an issue in terms of decoding and converting file formats on the backend. Even if that were the case, I'm certain there is some commercial license software they could purchase to do that for them. This isn't an open-source endeavor, and they charge each student to take the exam.