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The tool presented in this paper performs an automatic segmentation of stereoscopic image sequences, based on the modeling of distance maps obtained by image processing. Two three-dimensional (3-D) image analysis algorithms are combined: i) estimation of dense depth maps from stereoscopic image sequences and ii) depth-based object segmentation. A Markovian statistical approach for such a segmentation of a dense depth map into arbitrarily shaped and oriented planar surfaces is described in detail. The simulation results on sequences 'Fun fair' and 'Tunnel,' provided on video tape to the MPEG-4 tests of November 1995, are discussed. Index Terms - Binocular disparity, depth-based segmentation, depth estimation, Markovian statistical approach, object-based segmentation.

This paper describes a region-based coding algorithm developed by Thomson Multimedia and submitted to MPEG-4 tests of November 1995 and January 1996. In this algorithm, the segmentation into regions is based on an advanced motion analysis, successively achieving a multiresolution motion field estimation and a segmentation based on a Markovian statistical approach, which insures a good temporal coherence of segmentation maps and an identification of covered areas. Moreover, the accurate motion description allows an intermediate frames interpolation which can increase the displayed frame rate. Simulation results and MPEG-4 tests of January 1996 have shown that the algorithm is as efficient as block-based coding algorithms like MPEG-1 or H.263 for the compression functionality, while offering temporal scalability by higher frame rates. Moreover, description of the scene in coherent motion regions may be seen as an intermediate step toward object-based functionalities. Index Terms - Motion analysis, motion segmentation, MPEG-4, multimedia, region-based coding techniques, video compression.

Camcorder piracy refers to the process of using a camcorder to record a screen that displays copyrighted content. In contrast to the previous works that aimed at detecting the occurrence of camcorder piracy, this paper conducts an in-depth study of the luminance flicker that is naturally present in camcorded videos due to the interplay between a liquid-crystal-display (LCD) screen and a camcorder. We first model the flicker signal and show that its parameters are tied to such internal characteristics of the pirate devices as the back-light frequency of the LCD screen and the read-out time of the camcorder. We then present new estimation techniques to recover these hidden parameters directly from camcorded videos and demonstrate that such forensic cues could provide intelligence on the pirate devices. We also discuss how to recover the shape of the low-power flicker signal itself and show that it could be used to infer which back-light technology employed in the pirate LCD screen. [ABSTRACT FROM PUBLISHER]