UPMC at MediaEval 2013: Relevance by Text and Diversity by Visual Clustering

In the diversity task, our strategy was to, first, try to improve relevance, and then to cluster similar images to improve diversity. We propose a four step framework, based on AHC clustering and different reranking strategies. A large number of tests on devset showed that most of the best strategies include text based reranking for pertinence, and visual clustering for diversity even compared to location based descriptors. Results on expert and crowd-sourcing testset grounds truths seem to confirm these observations.