Well, if you test an algorithm that claims to have same image quality with smaller file size, you should compare images of the same quality and look at the file

Well, if you test an algorithm that claims to have same image quality with smaller file size, you should compare images of the same quality and look at the files size, not the other way round. Besides, I don't see why you need megabytes of photo data, regular internet photo data would have sufficed (for which the authors say they have developed webp anyways). I agree with your point that he included subjective evaluation, though.