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This paper provides an overview of the Social Event Detection (SED) task, which is organized as part of the MediaEval 2011 benchmarking activity. With the convergence between social networking and multimedia creation and distribution being experienced on a regular basis by hundreds of millions of people worldwide, this task examines how new or state of the(More)
This paper is concerned with the retrieval of images from large databases based on their shape similarity to a query image. Our approach is based on two dimensional histograms that encode both the local and global geometric properties of the shapes. The pair-wise attributes are the directed segment relative angle and directed relative position. The novelty(More)
In this paper, we propose a new type of multi-dimensional hidden Markov model based on the idea of dependency tree between positions. This simplification leads to an efficient implementation of the re-estimation algorithms, while keeping a mix of horizontal and vertical dependencies between positions. We explain DT-HMM and we present the formulas for the(More)
ÐThis paper presents a new compact shape representation for retrieving line-patterns from large databases. The basic idea is to exploit both geometric attributes and structural information to construct a shape histogram. We realize this goal by computing the N-nearest neighbor graph for the lines-segments for each pattern. The edges of the neighborhood(More)
This paper describes a graph-matching technique for recognising line-pattern shapes in large image databases. The methodological contribution of the paper is to develop a Bayesian matching algorithm that uses edge-consistency and node attribute similarity. This information is used to determine the a posteriori probability of a query graph for each of the(More)
We present a complete and efficient framework for video shot indexing and retrieval. Video shots are described by their key-frame, themselves described by their regions. Region-based approaches suffer from the complexity of segmentation and comparison tasks. A compact region-based shot representation is usually obtained thanks to vector-quantization method.(More)
In this paper we propose to compare two region-based approaches to content-based video indexing and retrieval. Namely a comparison of a system using the Earth Mover's Distance and a system using the Latent Semantic Indexing is provided. Region-based methods allow to keep the local information in a way that reflects the human perception of the content. Thus,(More)
In this paper, we present our approach and results of the MediaEval 2011 social event detection (SED) task. We solve the event detection problem in three steps. First, we query all event instances that happened given some condition. Then, an event identification model is proposed to measure the relationship between events and photos. Finally, visual pruning(More)