Section: Overall Objectives

Introduction

IMEDIA2 is an extension of IMEDIA team for one more year. Its overall objectives remain the same.

One of the consequences of the increasing ease of use and significant cost reduction of computer systems is the production and exchange of more and more digital and multimedia documents. These documents are fundamentally heterogeneous in structure and content as they usually contain text, images, graphics, video and sounds and may contain 3D objects. Information retrieval can no longer rely on text-based queries alone; it will have to be multi-modal and to integrate all the aspects of the multimedia content. In particular, the visual content has a major role and represents a central vector for the transmission of information. The description of that content by means of image analysis techniques is less subjective than the usual keyword-based annotations, whenever they exist. Moreover, being independent from the query language, the description of visual content is becoming paramount for the efficient exploration of a multimedia stream. In the IMEDIA2 group we focus on the intelligent and efficient access by visual content. With this goal in mind, we develop methods that address key issues such as content-based indexing, interactive search and image database navigation, in the context of multimedia content (text, image, video, 3D models). Content-based image retrieval systems provide help for the automatic search and assist human decisions. The user remains the maître d'oeuvre, the only one able to take the final decision. The numerous research activities in this field during the last decade have proved that retrieval based on the visual content was feasible. Nevertheless, current practice shows that a usability gap remains between the designers of these techniques/methods and their potential users. One of the main goals of our research group is to reduce the gap between the real usages and the functionalities resulting from our research on visual content-based information retrieval. Thus, we apply ourselves to conceive methods and techniques that can address realistic scenarios, which often lead to exciting methodological challenges. Among the "usage" objectives, an important one is the ability, for the user, to express his specific visual interest for a part of a picture. It allows him to better target his intention and to formulate it more accurately. Another goal in the same spirit is to express subjective preferences and to provide the system with the ability to learn those preferences. When dealing with any of these issues, we keep in mind the importance of the scalability of such interactive systems in terms of indexing and response times. Of course, what value these times should have and how critical they are depend heavily on the domain (specific or generic) and on the cost of the errors. Our research work is then at the intersection of several scientific domains. The main ones are image analysis, pattern recognition, statistical learning, human-machine interaction and database systems. It is structured into the following main themes:

1. 2D or 3D indexing: this part mainly concerns modeling the visual aspect of images and of 3D shapes, by means of image analysis techniques. It leads to the design of signatures that can then be obtained automatically.

2. feature space structuring: to increase in efficiency the search by content in very large collections of images.

More generally, the research work and the academic and industrial collaborations of the IMEDIA2 team aim to answer the complex problem of the intelligent and efficient access to multimedia content.