Recently Savvas Chatzichristofis released a Facebook app based on his tool img(Rummager) to retrieve the photos of Facebook contacts based on image content. The tool – called img(Finder) – allows to connect to a Facebook account and creates an index based on the CEDD and FCTH image features. img(Finder) indexes the images of all Facebook friends. Querying the index is done by sketch (painting tool is included) or by sample image. Best of all: The tool is open source 
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