C. Labit

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Rate-distortion optimized region-based video coder

Proceedings 1999 International Conference on Image Processing (Cat. 99CH36348)

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Coarse Parallelization of Motion Estimation

Motion estimation is crutial in domains such as robot vision or image sequence coding. Fast or re... more Motion estimation is crutial in domains such as robot vision or image sequence coding. Fast or real time computing is often required but is problematic due to computational complexity. In this paper, an algorithm using multiresolution multigrid Markov random fields will be parallized. Such realizations have already been studied for fine parallelizations on massively parallel machines. The goal of this paper is to achieve a coarse parallelization on a workstations network, using PVM. Keywords : PVM, optical flow, multigrid deterministic relaxation 1 Introduction Motion estimation is used in many technical area. Image sequence compression requires motion estimation between frames to improve coding efficiency [18, 20, 14]. Robot vision, tracking, also rely on motion estimation algorithms. This paper will focus interest on energy-based motion estimation algorithm. Many tasks in computer vision and image analysis can be expressed as global optimization problems [3, 14, 16]. The general i...

Spatio-temporal wavelet transforms for image sequence analysis

1996 8th European Signal Processing Conference (EUSIPCO 1996), 1996

This paper intends to present an integrated approach of constructing new spatio-temporal wavelets... more This paper intends to present an integrated approach of constructing new spatio-temporal wavelets for discrete signal analysis. The main illustrative field of applications considered here stands as the analysis of digital image sequences. Nevertheless, this can be readily extended to any kind of spatio-temporal signals. Continuous wavelet transforms, continuous series, discretized series and discrete transforms are considered here in an unified way. The analysis to be developed relies only on dynamic parameters like uniform translation and rotation, on kinematic parameters like velocity and speed and on structural parameters as scale and orientation. This digital processing intends to cover the detection and the focalization on motion-based regions of interest in order to perform tracking, classification, segmentation, multiscale trajectory construction and eventually a selective reconstruction of the useful content.

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Motion-compensated adaptive wavelet filtering for image sequence processing

1995 International Conference on Acoustics, Speech, and Signal Processing, 1995

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Représentations parcimonieuses par un dictionnaire à structure adaptative: application au codage d'images satellitaires

Dans un contexte de codage d'images satellitaires, une structure de dictionnaire adaptative e... more Dans un contexte de codage d'images satellitaires, une structure de dictionnaire adaptative est apprise afin de representer les donnees de facon parcimonieuse tout en optimisant le compromis entre l'erreur d'approximation et le cout de codage. Cette nouvelle structure de dictionnaire, dite en "cerf-volant", s'adapte aux donnees d'apprentissage et peut etre consideree comme une evolution d'une structure en arbre. Une methode de selection des atomes au sein de cette structure, appelee Selection Adaptative des Atomes par Niveau (SAAN), est egalement presentee. Elle permet de selectionner un ou plusieurs atomes par niveau selon un critere de qualite de la representation. Un gain en debit-distorsion est observe pour la structure en "cerf-volant" par rapport aux dictionnaires dits "plats" (K-SVD, DCT) et par rapport a une structure arborescente, dont les niveaux sont de plus en plus vides et donc de moins en moins efficaces.

Joint Estimation of Motion and Illumination Variations for Coding of Image Sequences

This paper describes a new approach to the problem of motion estimation for the coding of image s... more This paper describes a new approach to the problem of motion estimation for the coding of image sequences. The goal is to obtain an efficient description (parametrization) of temporal variations between two successive images in a sequence. To achieve this we propose to use the standard hypothesis of luminance constancy along a motion trajectory simultaneously introducing a polynomial representation of illumination variations. The estimation process consists of two iteratively alternating stages: a region-based estimation of apparent 2D motion parameters and an estimation of 2D illumination variations. Such an approach reduces the residual reconstruction error after motion compensation due to improved estimation of motion parameters. 1 Introduction In the coding of image sequences, apparent motion permits the reconstruction of an image through motion compensation; only the preceding image and motion information have to be known. The information about pixel movements may be local, as ...

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Définition quantitative des matrices de pondération psychovisuelles pour la quantification adaptée en codage sous-bandes d'images

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Coarse Parallelization of Motion

Motion Analysis for Image Sequence Coding

Part 1 Introduction to image sequence coding: digital picture sequences transmission and storage ... more Part 1 Introduction to image sequence coding: digital picture sequences transmission and storage systems extraction and exploitation of inter-frame correlations types of compression methods coding and motion plan of the book appendices. Part 2 Perception of time-varying images: modelling aspects principal results in the visual analysis of motion motion perception by selective filters motion perception and application to coding schemes appendices. Part 3 Two-dimensional motion analysis: 2-D velocity field and optical flow curvilinear domain two-dimensional domain appendices. Part 4 Motion-compensated predictive coding: a note on predictive coding rate-distortion function motion-compensated prediction quantization of the prediction errors information encoding channel errors appendices. Part 5 Hybrid coding - motion compensation and orthogonal transformation: rate-distortion function quantization of transform coefficients data encoding channel error appendix. Part 6 Multigride motion e...

Schémas d'estimation de mouvement multirésolution -multigrille en codage de séquences d'images

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Suivi de segmentation spatio-temporelle pour la compression de séquences animées

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Codage avec pertes de mosaïques vidéo selon un critère MDL

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Multi-Resolution Mesh-Based Motion

This paper introduces a mesh-based motion estimation scheme for image sequences and nodal motion ... more This paper introduces a mesh-based motion estimation scheme for image sequences and nodal motion vectors optimization by using a multi-resolution differential method. Because our final aim is mesh tracking throughout a video sequence, neither backward tracking nor forward tracking is well suited. The backward tracking provides good results when simply applied to two successive images, but it is damaged by the initial mesh which can not generally be considered as known on the last frame. Likewise, forward tracking suffers from an analysis/synthesis problem but it allows long time trackings. The motivation of our work is to take advantage of both forward tracking (which enables tracking) and backward tracking (for its efficiency) in a "backward in forward" method. To illustrate the proposed method, first results concerning the motion compensation of a mesh are shown and compared to the usual forward approach for one single mesh level, with or without multiresolution.

Quantification vectorielle algébrique et arborescente : méthode d'actualisation du dictionnaire. Application au codage vidéo

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<title>A polygon soup representation for free viewpoint video</title>

Three-Dimensional Image Processing (3DIP) and Applications, 2010

This paper presents a polygon soup representation for multiview data. Starting from a sequence of... more This paper presents a polygon soup representation for multiview data. Starting from a sequence of multi-view video plus depth (MVD) data, the proposed representation takes into account, in a unified manner, different issues such as compactness, compression, and intermediate view synthesis. The representation is built in two steps. First, a set of 3D quads is extracted using a quadtree decomposition

Planar facets segmentation using a multiresolution dense disparity field estimation

Proceedings 1998 International Conference on Image Processing. ICIP98 (Cat. No.98CB36269), 1998

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Compact quad-based representation for 3D video

2009 3DTV Conference: The True Vision - Capture, Transmission and Display of 3D Video, 2009

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Bit rate and local quality control for on-board satellite image compression

Proceedings DCC 2000. Data Compression Conference, 2000

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<title>Mesh-based scalable image coding with rate-distortion optimization</title>

Image and Video Communications and Processing 2000, 2000

ABSTRACT Recent development in video coding research deals with the use of hierarchical and/or ad... more ABSTRACT Recent development in video coding research deals with the use of hierarchical and/or adaptative mesh for video representation. Concurrently, transmitted bit rates have to be reduced to adapt to the network available bandwidth. Some previous works deal with adaptative node sampling according to image content. However, adaptative hierarchical proposed approaches do not optimize a compromise between distortion and bitrate: the representation coding cost is often stated but not taken into account as a constraint. Compared to these methods, this paper proposes for considering an adaptative hierarchical mesh based representation whose splitting criterion optimizes both the coding cost and the image rendering. Jointly, node value optimization, adaptative quantization, cheap coding tree and a wavelet approach are presented. To illustrate our different proposed methods, experimental results are shown and compared to the JPEG picture coding format.