Mouna Torjmen

Using textual and structural context for searching Multimedia Elements

We investigate in this paper the use of XML structure in multimedia retrieval, particularly in context-based image retrieval. We propose two methods to represent multimedia objects: the first one is based on an implicit use of textual and structural context of multimedia objects, whereas the second one is based on an explicit use of both sources. Experimental evaluation is carried out using the INEX MultimediaFragments Task 2006 and 2007. We show that there is a strong vocabulary relation between the query and the multimedia object representation, and that using XML structure improves significantly the effectiveness of multimedia retrieval.

Using Pseudo-Relevance Feedback to Improve Image Retrieval Results

In this paper, we propose a pseudo-relevance feedback method to deal with the photographic retrieval and medical retrieval tasks of ImageCLEF 2007. The aim of our participation to ImageCLEF is to evaluate a combination method using both english textual queries and image queries to answer to topics. The approach processes image queries and merges them with textual queries in order to improve results. A first set of expirements using only textual information does not allow to obtain good results. To process image queries, we used the FIRE system to sort similar images using low level features, and we then used associated textual information of the top images to construct a new textual query. Results showed the interest of low level features to process image queries, as performance increased compared to textual queries processing. Finally, best results were obtained combining the results lists of textual queries processing and image queries processing with a linear function.

XML Multimedia Retrieval: From Relevant Textual Information to Relevant Multimedia Fragments

In this paper, we are interested in XML multimedia document retrieval, whose aim is to find relevant multimedia components (i.e. XML fragments containing another media than text) that focus on the user needs. The work described here is carried out with images, but can be extended to any other media. We propose an XML multimedia fragment retrieval approach based on two steps. In a first step, we search for relevant images and then we retrieve the best multimedia fragments corresponding to these images. Image retrieval is done using textual and structural information from ascendant, sibling and direct descendant nodes in the XML tree, while multimedia fragment retrieval is done by evaluating the score of ancestors of images retrieved in the first step. Experiments were done on the INEX 2006 and 2007 Multimedia Fragments task and show the interest of our method.

Evaluating the impact of image names in context-based image retrieval

This paper describes our work at the CLEF 2008 WikipediaMM Task. We study the use of image name in a context-based image retrieval approach. This factor is evaluated in three manners. The first one consists of using image names explicitly: we computed a similarity score between the query and the name of images using the vector space model. The second one consists of combining results obtained using the textual content of documents and results obtained using the first method. Finally, in our last approach, image names are used less explicitly: we proposed to use all the textual content of image annotations, but we increased the weight of terms in the image name. Results show that the image name can be an interesting factor to improve image retrieval results.

Towards a structure-based multimedia retrieval model

In this paper, we are interested in multimedia XML document retrieval, whose aim is to find relevant document components (i.e XML elements) that focus on the user needs. We propose to represent multimedia elements using not only textual information, but also hierarchical structure. Indeed, an XML document can be represented as a tree, whose nodes correspond to XML elements. Thanks to this representation, an analogy between XML documents and ontologies can be established. Therefore, to quantify the participation degree of each node in the multimedia element representation, we propose two measures using the ontology hierarchy. Another part of our model consists of defining the best window of multimedia fragments to be returned to the user. Through the evaluation of our model on the INEX 2006 Multimedia Fragments Task, we show the importance of using the document structure in multimedia information retrieval.

XFIRM at INEX 2006. Ad-Hoc, Relevance Feedback and MultiMedia Tracks

This paper describes experiments carried out with the XFIRM system in the INEX 2006 framework. The XFIRM system uses a relevance propagation method to answer CO and CO+S queries. Runs were submitted to the ad-hoc, relevance feedback and multimedia tracks.