Tatouage du flux compressé MPEG-4 AVC

La présente thèse aborde le sujet de tatouage du flux MPEG-4 AVC sur ses deux volets théoriques et applicatifs en considérant deux domaines applicatifs à savoir la protection du droit d auteur et la vérification de l'intégrité du contenu. Du point de vue théorique, le principal enjeu est de développer un cadre de tatouage unitaire en mesure de servir les deux applications mentionnées ci-dessus. Du point de vue méthodologique, le défi consiste à instancier ce cadre théorique pour servir les applications visées. La première contribution principale consiste à définir un cadre théorique pour le tatouage multi symboles à base de modulation d index de quantification (m-QIM). La règle d insertion QIM a été généralisée du cas binaire au cas multi-symboles et la règle de détection optimale (minimisant la probabilité d erreur à la détection en condition du bruit blanc, additif et gaussien) a été établie. Il est ainsi démontré que la quantité d information insérée peut être augmentée par un facteur de log2m tout en gardant les mêmes contraintes de robustesse et de transparence. Une quantité d information de 150 bits par minutes, soit environ 20 fois plus grande que la limite imposée par la norme DCI est obtenue. La deuxième contribution consiste à spécifier une opération de prétraitement qui permet d éliminer les impactes du phénomène du drift (propagation de la distorsion) dans le flux compressé MPEG-4 AVC. D abord, le problème a été formalisé algébriquement en se basant sur les expressions analytiques des opérations d encodage. Ensuite, le problème a été résolu sous la contrainte de prévention du drift. Une amélioration de la transparence avec des gains de 2 dB en PSNR est obtenueThe present thesis addresses the MPEG-4 AVC stream watermarking and considers two theoretical and applicative challenges, namely ownership protection and content integrity verification.From the theoretical point of view, the thesis main challenge is to develop a unitary watermarking framework (insertion/detection) able to serve the two above mentioned applications in the compressed domain. From the methodological point of view, the challenge is to instantiate this theoretical framework for serving the targeted applications. The thesis first main contribution consists in building the theoretical framework for the multi symbol watermarking based on quantization index modulation (m-QIM). The insertion rule is analytically designed by extending the binary QIM rule. The detection rule is optimized so as to ensure minimal probability of error under additive white Gaussian noise distributed attacks. It is thus demonstrated that the data payload can be increased by a factor of log2m, for prescribed transparency and additive Gaussian noise power. A data payload of 150 bits per minute, i.e. about 20 times larger than the limit imposed by the DCI standard, is obtained. The thesis second main theoretical contribution consists in specifying a preprocessing MPEG-4 AVC shaping operation which can eliminate the intra-frame drift effect. The drift represents the distortion spread in the compressed stream related to the MPEG encoding paradigm. In this respect, the drift distortion propagation problem in MPEG-4 AVC is algebraically expressed and the corresponding equations system is solved under drift-free constraints. The drift-free shaping results in gain in transparency of 2 dB in PSNREVRY-INT (912282302) / SudocSudocFranceF

Tatouage du flux compressé MPEG-4 AVC

The present thesis addresses the MPEG-4 AVC stream watermarking and considers two theoretical and applicative challenges, namely ownership protection and content integrity verification.From the theoretical point of view, the thesis main challenge is to develop a unitary watermarking framework (insertion/detection) able to serve the two above mentioned applications in the compressed domain. From the methodological point of view, the challenge is to instantiate this theoretical framework for serving the targeted applications. The thesis first main contribution consists in building the theoretical framework for the multi symbol watermarking based on quantization index modulation (m-QIM). The insertion rule is analytically designed by extending the binary QIM rule. The detection rule is optimized so as to ensure minimal probability of error under additive white Gaussian noise distributed attacks. It is thus demonstrated that the data payload can be increased by a factor of log2m, for prescribed transparency and additive Gaussian noise power. A data payload of 150 bits per minute, i.e. about 20 times larger than the limit imposed by the DCI standard, is obtained. The thesis second main theoretical contribution consists in specifying a preprocessing MPEG-4 AVC shaping operation which can eliminate the intra-frame drift effect. The drift represents the distortion spread in the compressed stream related to the MPEG encoding paradigm. In this respect, the drift distortion propagation problem in MPEG-4 AVC is algebraically expressed and the corresponding equations system is solved under drift-free constraints. The drift-free shaping results in gain in transparency of 2 dB in PSNRLa présente thèse aborde le sujet de tatouage du flux MPEG-4 AVC sur ses deux volets théoriques et applicatifs en considérant deux domaines applicatifs à savoir la protection du droit d’auteur et la vérification de l'intégrité du contenu. Du point de vue théorique, le principal enjeu est de développer un cadre de tatouage unitaire en mesure de servir les deux applications mentionnées ci-dessus. Du point de vue méthodologique, le défi consiste à instancier ce cadre théorique pour servir les applications visées. La première contribution principale consiste à définir un cadre théorique pour le tatouage multi symboles à base de modulation d’index de quantification (m-QIM). La règle d’insertion QIM a été généralisée du cas binaire au cas multi-symboles et la règle de détection optimale (minimisant la probabilité d’erreur à la détection en condition du bruit blanc, additif et gaussien) a été établie. Il est ainsi démontré que la quantité d’information insérée peut être augmentée par un facteur de log2m tout en gardant les mêmes contraintes de robustesse et de transparence. Une quantité d’information de 150 bits par minutes, soit environ 20 fois plus grande que la limite imposée par la norme DCI est obtenue. La deuxième contribution consiste à spécifier une opération de prétraitement qui permet d’éliminer les impactes du phénomène du drift (propagation de la distorsion) dans le flux compressé MPEG-4 AVC. D’abord, le problème a été formalisé algébriquement en se basant sur les expressions analytiques des opérations d’encodage. Ensuite, le problème a été résolu sous la contrainte de prévention du drift. Une amélioration de la transparence avec des gains de 2 dB en PSNR est obtenu

Semi-fragile watermarking for video surveillance applications

International audienceThis paper advances SPYART, a novel semi-fragile watermarking scheme for MPEG-4 AVC protection. The authentication information, granting the method fragility, is provided by the Intra prediction mode types. This signature is embedded in the quantized error prediction of the DCT coefficients by an m-QIM technique, thus ensuring the method robustness. SPYART was evaluated under the framework of a videosurveillance application; the results exhibit fragility to content replacement (with an 1/81 frame and 3s spatial and temporal accuracy, respectively) and robustness against transcoding (MPEG-4 AVC compression by a factor of 4). As both the signature extraction and mark embedding take place at the MPEG-4 AVC syntax element level, the method also features low complexity

MPEG-4 AVC saliency map computation

International audienceA saliency map provides information about the regions inside some visual content (image, video, ...) at which a human observer will spontaneously look at. For saliency maps computation, current research studies consider the uncompressed (pixel) representation of the visual content and extract various types of information (intensity, color, orientation, motion energy) which are then fusioned. This paper goes one step further and computes the saliency map directly from the MPEG-4 AVC stream syntax elements with minimal decoding operations. In this respect, an a-priori in-depth study on the MPEG-4 AVC syntax elements is first carried out so as to identify the entities appealing the visual attention. Secondly, the MPEG-4 AVC reference software is completed with software tools allowing the parsing of these elements and their subsequent usage in objective benchmarking experiments. This way, it is demonstrated that an MPEG-4 saliency map can be given by a combination of static saliency and motion maps.This saliency map is experimentally validated under a robust watermarking framework. When included in an m-QIM (multiple symbols Quantization Index Modulation) insertion method, PSNR average gains of 2.43 dB, 2.15dB, and 2.37 dB are obtained for data payload of 10, 20 and 30 watermarked blocks per I frame, i.e. about 30, 60, and 90 bits/second, respectively. These quantitative results are obtained out of processing 2 hours of heterogeneous video content

MPEG-4 AVC stream-based saliency detection: application to robust watermarking

International audienceBy bridging uncompressed-domain saliency detection and MPEG-4 AVC compression principles, the present paper advances a methodological framework for extracting the saliency maps directly from the stream syntax elements. In this respect, inside each GOP, the intensity, color, orientation and motion elementary saliency maps are related to the energy of the luma coefficients, to the energy of chroma coefficients, to the gradient of the prediction modes and to the amplitude of the motion vectors, respectively. The three spatial saliency maps are pooled according to an average formula, while the static-temporal fusion is achieved by six different formulas. The experiments consider both ground-truth and applicative evaluations. The ground-truth benchmarking investigates the relation between the predicted MPEG-4 AVC saliency map and the actual human saliency, captured by eye-tracking devices. It is based on two corpora (representing density fixation maps and saccade locations), two objective criteria (related to the closeness between the predicted and the real saliency maps and to the difference between the behavior of the predicted saliency map in fixation and random locations), two objective measures (KLD – the Kullback Leibler Divergence and AUC – the Area Under the ROC Curve) and 5 state-of-the-art saliency models (3 acting in spatial domain and 2 acting in compressed domain). The applicative validation is carried out by integrating the MPEG-4 AVC saliency map into a robust watermarking application. As an overall conclusion, the paper demonstrates that although the MPEG-4 AVC standard does not explicitly relies on any visual saliency principle, its stream syntax elements preserve this property. Four main benefits for the MPEG-4 AVC based saliency extraction are thus brought to light: (1) it outperforms (or, at least, is as good as) state-of-the-art uncompressed domain methods, (2) it allows significant gains to be obtained in watermarking transparency (for prescribed data payload and robustness), (3) it is less sensitive to the randomness in the processed visual content, and (4) it has a linear computational complexity. For instance, the ground truth results exhibit absolute relative gains between 60% and 164% in KLD, between 17% and 21% in AUC, and relative gains in KLD sensitivity between 1.18 and 6.12 and in AUC sensitivity between 1.06 and 33.7; the applicative validation brings to light transparency gains up to 10 dB in PSNR