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Carl Frélicot - IEEE Xplore Author Profile

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Background subtraction (BS) is one of the key steps for detecting moving objects in video surveillance applications. In the last few years, many BS methods have been developed to handle the different challenges met in video surveillance but the role and the relevance of the visual features used has been less investigated. In this paper, we present an Online Weighted Ensemble of One-Class SVMs (Sup...Show More
An new pixel unsupervised hyperspectral image (HSI) segmentation method is proposed. It relies on a binary incoding of spectral reflectance curve variations of pixels that allows to consider HSI segmentation as a clustering problem in the feature set of binary strings. Using a generalized Hamming distance, a k-modes algorithm is applied to obtain a cluster partionning of the HSI with no use of any...Show More
This article addresses the problem of the construction of concordance measures between two crisp, fuzzy and possibilistic partitions from their coincidence matrices. Two existing approaches are reviewed and their advantages and drawbacks are exhibited so that a new Rand index taking profits of both is proposed. Numerous experimental results show that it outperforms other extensions of the Rand ind...Show More
Since a clustering algorithm can produce as many partitions as desired, one needs to assess their quality in order to select the partition that most represents the structure in the data, if there is any. This is the rationale for the cluster-validity (CV) problem and indices. This paper presents a CV index that helps to find the optimal number of clusters of data from partitions generated by a fuz...Show More
Most already existing indices used to compare two strict partitions with different number of clusters are based on coincidence matrices. To extend such indices to fuzzy partitions, one can define fuzzy coincidence matrices by means of triangular norms. It has been shown this can require some kind of normalization to reinforce the corresponding indices. We propose in this paper a generic solution t...Show More
Decision-making systems intend to copy human reasoning which often consists in eliminating highly non probable situations (e.g. diseases, suspects) rather than selecting the most reliable ones. In this paper, we present the concept of class-rejective rules for pattern recognition. Contrary to usual reject option schemes where classes are selected when they may correspond to the true class of the i...Show More
This paper addresses the problem of region-based color image segmentation using a fuzzy clustering algorithm, e.g. a spatial version of fuzzy c-means, in order to partition the image into clusters corresponding to homogeneous regions. We propose to determine the optimal number of clusters, and so the number of regions, by using a new cluster validity index computed on fuzzy partitions. Experimenta...Show More
In this paper, we present new fuzzy connectives that allow to specify an order to the considered operation. These operators are generalization of usual fuzzy connectives, i.e. triangular norms and triangular conorms. A potential use of the proposed operators consists in assessing to what extent several values are high or low in unconstrained fuzzy sets is given. We also present weighted k-order fu...Show More
This paper presents a new approach to find the optimal number of clusters of a fuzzy partition. It is based on a fuzzy modeling approach which combines measures of clusters' separation and overlap. Theses measures are based on triangular norms and a discrete Sugeno integral. Results on artificial and real data sets prove its efficiency compared to indexes from the literature.Show More
Overlapping classes and outliers can significantly decrease a classifier performance. We address here the problem of giving a classifier the ability to reject some patterns either for ambiguity or for distance in order to improve its performance. Given a set of typicality degrees for a pattern to be classified, we use an operator based on triangular norms and a discrete Sugeno integral to quantify...Show More
In many fields, e.g. decision-making, numerical values in [0,1] are available and one is often interested in detecting which are similar. In this paper, we propose an operator which is able to detect whether some values can be gathered by blocks with respect to their similarity or not. It combines the values and a kernel function using triangular norms and Sugeno integrals. This operator allows to...Show More
Content-based copy retrieval (CBCR) aims at retrieving in a database all the modified versions or the previous versions of a given candidate object. In this paper, we present a copy-retrieval scheme based on local features that can deal with very large databases both in terms of quality and speed. We first propose a new approximate similarity search technique in which the probabilistic selection o...Show More
Cluster validity indexes aim at evaluating the degree to which a partition obtained from a clustering algorithm approximates the real structure of a data set. Most of them reduce to the search of the right number of clusters. This paper presents such a new validity index for fuzzy clustering based on the aggregation of the resulting membership degrees with no additional information, e.g. lite geom...Show More
Content-based copy detection (CBCD) is one of the emerging multimedia applications for which there is a need of a concerted effort from the database community and the computer vision community. Recent methods based on interest points and local fingerprints have been proposed to perform robust CBCD of images and video. They include two steps: the search of similar fingerprints in the database and a...Show More
Recent methods based on interest points and local fingerprints have been proposed to perform robust CBCD (content-based copy detection) of images and video. They include two steps: the search for similar local fingerprints in the database (DB) and a voting strategy that merges all the local results in order to perform a global decision. In most image or video retrieval systems, the search for simi...Show More
In many image or video retrieval systems, the search for similar objects in the database includes a spatial access method to a multidimensional feature space. This step is generally considered as a problem independent of the features and the similarity type. The well known multidimensional nearest neighbor search has also been widely studied by the database community as a generic method. We propos...Show More
This paper presents part of the work aiming at building a tool for the detection of graphomotor difficulties involving disorders in the writing of children. We have defined an experimental protocol, containing exercises such as copying figures or writing sentences under different conditions. It allows to measure simple aspects of graphomotor skill up to complex ones. A great number of features wer...Show More
The design of a rejection-based classifier can be made according to two well-identified strategies operating in two sequential steps: the accept-first strategy and the reject-first one. The first one is the most usual. Recently, we have proposed a general class of the latter classifiers using fuzzy XOR operators based on dual triples (t-norm, t-conorm, complement) (2001). In this paper, we investi...Show More
The authors address the problem of defining a general class of reject-first possibilistic classifiers. It relies on fuzzy XOR operators based on dual triples (t-norm, t-conorm, complement). Such a classifier operates in two sequential steps. It starts with testing for exclusive classification by thresholding the fuzzy XOR combination of membership degrees to the different classes. If the pattern h...Show More
In the context of pattern classification with two-fold reject options (ambiguity and distance), we have identified different strategies leading to two-stage classifiers. Strategies differ on managing both types of rejection (independently or not). The paper addresses the problem of combining the first stage of rejection-based classifiers of each strategy. A Dempster-Shafer model is designed. Its m...Show More
This article deals with the combination of the first stage of two-fold rejection-based classifiers for pattern classification. This Dempster-Shafer's model-based combination uses some relevant characteristics of the different two-stage classifier strategies we have identified. These strategies differ on the managing of the ambiguity and distance rejection (independently or not). We propose some cl...Show More
In the general framework of pattern classification two reject strategies are identified. These classifiers are defined as a couple of labeling and hardening functions. In this paper the first stage of classifiers belonging to each strategy are used in turn and their results are combined with a Dempster-Shafer model to classify or reject patterns. Results on artificial data are provided.Show More
Deals with the pretopological approach to the supervised pattern classification problem. An improved learning process which results in a reduced number of neighborhoods to be learned is proposed. We also present extensions concerning the use of different metrics in the /spl isin/-neighborhood definition in order to improve the class boundaries. Performances in terms of storage requirements, comput...Show More
This paper presents a rejection-based and class-selective possibilistic classifier and its parameters learning. The classifier is defined as a couple of functions (D,T), D being a labelling one and T being a hardening one in a non-exclusive way. The parameters of the classifier (D,T), whose strategy for rejection is not classical, are learned using a suitable clustering algorithm and statistical o...Show More
This paper aims at presenting different classifiers (classification rules) with two characteristics. First, they are based on multiprototype fuzzy labels which are combined using connectives (t-conorms). Thus, the definition of the classes increases and consequently the classifier performance. Second, the rules include reject options. They allow the classifiers to manage uncertainty due to both im...Show More