Abstract: Image retrieval systems are user-oriented.Diversity of retrieval results has different effects on users’ experie-nces depending on their intents.Some users may need those different but similar results,which means higher diversity.Nevertheless current retrieval system which is majorly based on query keywords can hardly capture users’ intents directly from their query.Thus,a new interactive element,zoom factor,was introduced into retrieval system to bridge the gap between users’ intents and the diversity of retrieval results.This enables users to directly control the diversity of results.We first obtained images returned by retrieval system.And then the visual and semantic distances of each other were computed.Hierarchical clustering was then used to form a clustering tree.And finally we controlled the expansion of a sub-tree with users’ directly tune of zoom factor.For each expanded sub-tree,the node with the lowest index in the original results was selected as the representative.

Key words: Image retrieval,Relevance Feedback,Diversity,Hierarchical clustering