Are two pictures better than one?

A major hurdle in practical content based image retrieval (CBIR) is conveying the user´s information need to the system. One common method of query specification is to express the query using one or more example images. The authors consider whether using more examples improves the effectiveness of CBIR in meeting a user´s information need. We show that using multiple examples improves retrieval effectiveness by around 9%-20% over single-example queries, but that further improvements in using more than two examples may not justify the added processing required