Web-Scale Multimedia Analysis: Does Content Matter?
It's important to state that one can't prove a negative conjecture. The authors are asking whether they get more information from the pixels or from the metadata. They humans are exceptionally good at judging the content of a picture. Of course that is a cat. And if it's not something they can tell from a photo (such as whether the cat is male or female), they don't think it's an important problem. In many problems, they are asking their algorithms if they can tell a difference, and they can't say whether their insight into the problem is weak, or if the information is just not present in the signal.