Eduardo Valle’s Blog

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Archive for January, 2010

Paper Accepted at MIR 2010

Posted by eduardovalle on Friday, January 22, 2010

Our paper, “Learning to Rank for Content-Based Image Retrieval” , was accepted at the upcoming ACM Multimedia Information Retrieval Conference (MIR 2010). The first author is the M.Sc. student Fábio Faria, and the paper was co-authored with my Post Doc supervisor Ricardo Torres and several of our partners from UFMG, including Marcos Gonçalves, with whom we have an ongoing cooperation.

Here is the abstract:

“In Content-based Image Retrieval (CBIR), accurately ranking the returned images is of paramount importance, since users consider mostly the topmost results. The typical ranking strategy used by many CBIR systems is to employ image content descriptors, so that returned images that are most similar to the query image are placed higher in the rank. While this strategy is well accepted and widely used, improved results may be obtained by combining multiple image descriptors. In this paper we explore this idea, and introduce algorithms that learn to combine information coming from different descriptors. The proposed learning to rank algorithms are based on three diverse learning techniques: Support Vector Machines (CBIR-SVM), Genetic Programming (CBIR-GP), and Association Rules (CBIR-AR). Eighteen image content descriptors (color, texture, and shape information) are used as input and provided as training to the learning algorithms. We performed a systematic evaluation involving two complex and heterogeneous image databases (Corel e Caltech) and two evaluation measures (Precision and MAP). The empirical results show that all learning algorithms provide significant gains when compared to the typical ranking strategy  in which descriptors are used in isolation. We concluded that, in general, CBIR-AR and CBIR-GP outperforms CBIR-SVM. A fine-grained analysis revealed the lack of correlation between the results provided by CBIR-AR and the results provided by the other two algorithms, which indicates the opportunity of an advantageous hybrid approach.”

I will be travelling to Philadelphia on late March to present the poster. I am very excited about this upcoming trip to the United States, where I am to meet several friends and colleagues, but at the same time, worried about the radicalization of air security rules and the exaggeration of perception of threats. Have we got so scared to die that we decided instead not to live ?

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Lambda Calculus

Posted by eduardovalle on Monday, January 11, 2010

While we both enjoy our Summer breaks in our hometown, my good friend Bruno Abrahão, who is now a Ph.D. candidate at Cornell University, asked me if he could, as a preparation for an upcoming exam, teach me a lesson on Advanced Programming Languages. I eagerly accepted, not only for the opportunity of spending time with him, but also for the enjoyment of learning something new.

My last proper lesson on P.L. was on my undergrads, probably more than ten years ago. Certainly, it was nothing like the one he taught me: his course covered extremely abstract topics, mostly concerning deep formal issues, like how the semantics of P.L. can be constructed. We have started with lambda calculus, and from that innocent foundation, erected a progressively complex conceptual lattice…

I don’t know if he had planned a self-contained lesson, but as it turned out, we just greedily browsed the syllabus, stopping at everything that looked noteworthy. He would ask me “let me know when you get tired” and I would answer “not yet, please, go on”. We visited a lot of material, throwing haphazardly away everything whose “interest / length of exposition” ratio seemed unpromising.

When we finally became aware of the time, four hours had passed, and we were so exhausted we could barely say our goodbyes in a proper manner.

But I am looking forward to do this again and pondering on how can I lure each one of my friends into teaching me a lesson. Maybe some Earl Gray and my famous banana cupcakes could do the trick…

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