There are several semantic sources that can be found in the Web that are
either explicit, e.g. Wikipedia, or implicit, e.g. derived from Web usage
data. Most of them are related to user generated content
(UGC) or what is called today the Web 2.0. In this talk we show how to use
these sources of evidence in Flickr, such as tags, visual annotations or
clicks, which represent the the wisdom of crowds behind UGC, to improve
image search. These results is the work of the multimedia retrieval team at
Yahoo! Research Barcelona and is part of a larger effort to produce a
virtuous data feedback circuit to leverage the Web itself.