Sylvie Jeannin

MPEG-7 visual motion descriptors

This paper describes tools and techniques for representing motion information in the context of MPEG-7 standardization for multimedia description interfaces. It first gives an overview of the current organization of the set of MPEG-7 motion descriptions, then illustrates this by presenting two of them, motion activity and motion trajectory, in more detail. It explains how to extract them from the content, how to express them in a compact way, and illustrates their use in concrete applications scenarios.

Segmentation-based video coding system allowing the manipulation of objects

This paper presents a generic video coding algorithm allowing the content-based manipulation of objects. This manipulation is possible thanks to the definition of a spatiotemporal segmentation of the sequences. The coding strategy relies on a joint optimization in the rate-distortion sense of the partition definition and of the coding techniques to be used within each region. This optimization creates the link between the analysis and synthesis parts of the coder. The analysis defines the time evolution of the partition, as well as the elimination or the appearance of regions that are homogeneous either spatially or in motion. The coding of the texture as well as of the partition relies on region-based motion compensation techniques. The algorithm offers a good compromise between the ability to track and manipulate objects and the coding efficiency.

Evolvable visual commercial detector

Commercial detection plays an important role in various video segmentation and indexing applications. It provides high-level program segmentation so that other algorithms can be applied on the true program material in the broadcast. It is a challenge to have robust commercial detection methodology for various platforms, content formats, and broadcast styles that are used all over the world. Wide deployment of such an algorithm not only requires the development of new algorithms but also updating and tuning of parameters for existing algorithms. We present visual commercial detectors that rely on features including, luminance, letterbox, and keyframe distance. These detectors were developed after a careful study of the various features that can be extracted during MPEG-encoding process in real time. Due to the intermittent nature of the features, and platform restrictions, the commercial detection relies on a set of thresholds to keep the implementation as simple as possible. We evolved these thresholds using genetic algorithms (GAs) to optimize the performance. We show how a scalar genetic algorithm can locate sets of parameters in a multi-objective space (precision and recall) that outperform the values selected by an expert engineer. We present the results of optimizing a commercial detection algorithm for different data sets and parameter sets. In this paper we show that GAs drastically improved our approach and enabled fast prototyping and performance tuning of commercial detection algorithms.

Motion descriptors for content-based video representation

This paper presents two motion descriptors which were recommended by MPEG to become part of the first visual reference model (XM 1.0) of the evolving MPEG-7 standard in development. These motion descriptors are: (i) the camera motion descriptor which describes the global motion of the camera or of the observer in a natural 3-D scene, and (ii) the object motion trajectory descriptor which describes how an object moves in 3-D space or in the 2-D image plane. These two descriptors are important elements in capturing the dynamic content of video sequences in a compact form. They are used to index video sequences according to their dynamic content. Applications that use these descriptors include TV program classification, video editing for broadcast TV and movies, broadcast sports, and video surveillance.

Video motion representation for improved content access

This paper describes techniques for representing motion information in the context of multimedia description interfaces (being standardized by MPEG-7). Focusing on camera motion and object trajectories, it shows how such descriptions can help consumers to browse and query through large audio-visual connections.

On the combination of a polynomial motion estimation with a hierarchical segmentation based video coding scheme

This article studies the cooperation between polynomial motion analysis and region-based video coding, in the context of multimedia dedicated video coding. It is based on the work made to develop a specific algorithm in this scope, but tries to stay as generic as possible. It first highlights the most important features of the polynomial region-based motion estimation method, and describes its implementation framework. Then, it analyzes the possibilities their combination is offering: improvement of the motion prediction quality, improvement of the codec compression performances, adaptability of the scheme to object-based functionalities.

A segmentation-based coding system allowing manipulation of objects (SESAME)

We present a coding scheme that achieves, for each image in the sequence, the best segmentation in terms of rate-distortion theory. It is obtained from a set of initial regions and a set of available coding techniques. The segmentation combines spatial and motion criteria. It selects at each area of the image the most adequate criterion for defining a partition in order to obtain the best compromise between cost and quality. In addition, the proposed scheme is very suitable for addressing content-based functionalities.