Windsurf: the best way to SURF: (and SIFT/BRISK/ORB/FREAK, too).

Despite their popularity, approaches based on salient point descriptors have yet to be proven effective for content-based image retrieval. In this paper, we show how the Windsurf library can be effectively exploited to assess a fair comparison among the existing alternative approaches based on salient points, which can be contrasted on aspects of both effectiveness and efficiency. Our extensive experimental evaluation, performed on four different image benchmarks, indeed, shows that techniques based on salient point descriptors have effectiveness not better than other existing techniques and are less amenable to be indexed, and thus, their efficiency remains questionable.