Browsing by Author "Bouchama, Samira"

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    A comparative study between compressed video watermarking methods based on DCT coefficients and intra prediction
    (2011-04-20) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Several watermarking methods have been applied to the newest video codec H.264/AVC to satisfy different applications such as authentication, tamper proof and copyright protection. Our objective through this paper is to present a comparative study between watermarking methods based on the quantized (Q) DCT coefficients and those based on the intra prediction of the 4x4 luma blocks, in terms of embedding capacity, video quality and bitrate. The use of intra prediction modes is motivating because it is possible to embed a relatively high embedding capacity while preserving the video quality; however it seems difficult to maintain the bitrate. In this paper we show that the Intra prediction based method outperforms the QDCT based method using the same codec configuration.
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    A comparative study between compressed video watermarking methods based on DCT coefficients and intra prediction
    (CERIST, 2011-09) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Several watermarking methods have been applied to the newest video codec H.264/AVC to satisfy different applications such as authentication, tamper proof and copyright protection. Our objective through this paper is to present a comparative study between watermarking methods based on the quantized (Q) DCT coefficients and those based on the intra prediction of the 4x4 luma blocks, in terms of embedding capacity, video quality and bitrate. The use of intra prediction modes is motivating because it is possible to embed a relatively high embedding capacity while preserving the video quality; however it seems difficult to maintain the bitrate. In this paper we show that the Intra prediction based method outperforms the QDCT based method using the same codec configuration.
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    Error Drift Compensation for Data Hiding of the H.264/AVC
    (Romanian Society of Control Engineering and Technical Informatics, 2013) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    The error propagation problem is one of the most attractive issues in the field of data hiding of compressed video because the achievement of several data hiding characteristics remains dependant on it. In this paper, a solution to compensate the error propagation is proposed for data hiding of the H.264/AVC. The error compensation is performed by a prior measurement of the introduced error in the watermarked block or in the neighbouring blocks. Two schemes are proposed: The first algorithm exploits the method of watermarking paired-coefficients in each block in order to bring the error to the middle of the block matrix. The distortion caused by each paired-coefficient is calculated in order to give a watermarking priority to the pairs which introduce the minimum error. In the second scheme, the error estimated in the neighbouring blocks is reduced from the residuals during the encoding process. In both schemes, results show that an important improvement of the video quality can be achieved and a good compromise is provided between the video distortion, the bitrate and the embedding.
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    Error Drift Compensation for Data Hiding of the H.264/AVC
    (CERIST, 2013) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    The error propagation problem is one of the most attractive issues in the field of data hiding of compressed video because the achievement of several data hiding characteristics remains dependant on it. In this paper, a solution to compensate the error propagation is proposed for data hiding of the H.264/AVC. The error compensation is performed by a prior measurement of the introduced error in the watermarked block or in the neighbouring blocks. Two schemes are proposed: The first algorithm exploits the method of watermarking paired-coefficients in each block in order to bring the error to the middle of the block matrix. The distortion caused by each paired-coefficient is calculated in order to give a watermarking priority to the pairs which introduce the minimum error. In the second scheme, the error estimated in the neighbouring blocks is reduced from the residuals during the encoding process. In both schemes, results show that an important improvement of the video quality can be achieved and a good compromise is provided between the video distortion, the bitrate and the embedding.
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    H.264/AVC Data Hiding Algorithm with a Limitation of the Drift Distortion
    (2012-10-21) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Many data hiding algorithms have been proposed for the latest video codec H.264/AVC, most of them are based on the 4x4 luma DCT coefficients. However, the drift distortion is the main reason which limits the embedding capacity in data hiding algorithms based on DCT coefficients. Few methods have been proposed to compensate or eliminate the error propagation. Though, they are either non-blind, only detectable or need prior knowledge of the encoded blocks and thus cannot be used for real time broadcasting. In this paper we show that it is possible to reduce considerably the error propagation for real time applications. The proposed algorithm exploits the method of watermarking paired-coefficients in each block in order to bring the error to the middle of the block matrix. We evaluate the distortion caused by each paired-coefficients in order to give a watermarking priority to the pairs which introduce the minimum error. The proposed scheme offers a very good compromise between the video distortion, the increase in bitrate and the embedding capacity
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    H.264/AVC Data Hiding Algorithm with a Limitation of the Drift Distortion
    (CERIST, 2012) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Many data hiding algorithms have been proposed for the latest video codec H.264/AVC, most of them are based on the 4x4 luma DCT coefficients. However, the drift distortion is the main reason which limits the embedding capacity in data hiding algorithms based on DCT coefficients. Few methods have been proposed to compensate or eliminate the error propagation. Though, they are either non-blind, only detectable or need prior knowledge of the encoded blocks and thus cannot be used for real time broadcasting. In this paper we show that it is possible to reduce considerably the error propagation for real time applications. The proposed algorithm exploits the method of watermarking paired-coefficients in each block in order to bring the error to the middle of the block matrix. We evaluate the distortion caused by each paired-coefficients in order to give a watermarking priority to the pairs which introduce the minimum error. The proposed scheme offers a very good compromise between the video distortion, the increase in bitrate and the embedding capacity.
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    H.264/AVC data hiding based on Intra prediction modes for real time applications
    (CERIST, 2012) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    A compromise is usually made between the different constraints of video data hiding methods, which seems more difficult to achieve for real time applications. In this paper, a new data hiding approach is presented for the video codec H.264/AVC. This method uses the intra prediction modes for the 4x4 luminance blocks. The objective is to ensure a high data embedding capacity and to preserve the encoding and the decoding times in order to satisfy real-time applications. The data embedding is based on changing a mode to the one of the closest direction. Good results have been obtained in terms of increasing the embedding capacity, maintaining the visual quality and limiting the additional processing time.
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    H.264/AVC Data Hiding Based on Intra Prediction Modes for Real-time Applications
    (2012-10-24) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    The existing data hiding methods for the newest video codec H.264/AVC exploit its several modules such as the discrete cosine transform coefficients or the prediction modes. In this paper, a new data hiding approach is presented by exploiting the intra prediction modes for the 4x4 luminance blocks. The objective is to ensure a relatively high embedding capacity and to preserve the encoding and the decoding times in order to satisfy real-time applications. The intra prediction modes are divided into four groups composed of modes of close prediction directions. The data embedding is based on modifying modes of the same group in order to maintain visual quality and limit the number of additional calculation procedures. The increase of embedding capacity relies on the group composed on four modes since it allows the embedding of two bits per mode.
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    Increase of embedding capacity of the H.264/AVC data hiding based on the intra-prediction modes
    (CERIST, 2011-09) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Data hiding methods applied to the newest video codec H.264/AVC are exploiting several modules of this codec such as the discrete cosine transform (DCT) coefficients and the intra prediction modes. The objective is to realize a good compromise between the embedding capacity, the increase in bitrate and the video quality, to satisfy several applications such as authentication or covert communication. In this paper we present a new approach to exploit the intra prediction modes for data hiding of the 4x4 luminance blocks. The objective is to ensure a good data embedding capacity and to preserve the encoding and the decoding times to satisfy reel time applications. The proposed method is based on dividing the intra prediction modes into four groups. Each group in composed of modes that have close prediction directions. Embedding the secret data is based on applying modification between modes of the same group in order to maintain visual quality and limit the number of additional calculation procedures. The increase of embedding capacity relies on the group composed on four modes since it allows the embedding of two bits per mode instead of one.
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    Les moyens techniques de protection des droits d’auteur : Apports du tatouage
    (2012-05-16) Bouchama, Samira; Aliane, Hassina; Bouder, Hadjira
    Avec le développement du réseau internet et des applications multimédias, de nouvelles craintes sont nées quant à la sécurité de ces documents et l’adaptation des dispositifs techniques de protection des droits d’auteur aux nouvelles technologies. En effet, si les données numériques sont sécurisées par des outils de cryptographie lors de leur transmission, elles ne le sont plus après réception et affichage. Ainsi, les données sont devenues aisément dupliquées, modifiées et diffusées rendant leur utilisation frauduleuse facile. A cet effet, les techniques de tatouage numérique ont été introduites initialement pour répondre aux besoins de la protection des droits d’auteur des documents multimédias en ligne. Ces techniques consistent à insérer dans un document des données (appelées marque ou signature) qui constitueraient une preuve de la paternité de l’œuvre face à toute utilisation illégale après réception du document. Dans cet article nous nous intéressons aux techniques de tatouage utilisées pour la protection des droits d’auteur. Nous présentons un état de l’art de ces techniques, leurs apports et limites pour la protection des droits d’auteurs et les critères à respecter pour les besoins de cette application. Nous présentons également quelques exemples de logiciels de tatouage disponibles sur le Web.
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    Les moyens techniques de protection des droits d’auteur :Apports du tatouage
    (CERIST, 2012) Bouchama, Samira; Aliane, Hassina; Bouder, Hadjira
    Avec le développement du réseau Internet et des applications multimédias, de nouvelles craintes sont nées quant à la sécurité de ces documents et l’adaptation des dispositifs techniques de protection des droits d’auteur aux nouvelles technologies. En effet, si les données numériques sont sécurisées par des outils de cryptographie lors de leur transmission, elles ne le sont plus après réception et affichage. Ainsi, les données sont devenues aisément dupliquées, modifiées et diffusées rendant leur utilisation frauduleuse facile. A cet effet, les techniques de tatouage numérique ont été introduites initialement pour répondre aux besoins de la protection des droits d’auteur des documents multimédias en ligne. Ces techniques consistent à insérer dans un document des données (appelées marque ou signature) qui constitueraient une preuve de la paternité de l’œuvre face à toute utilisation illégale après réception du document. Dans ce rapport nous nous intéressons aux techniques de tatouage utilisées pour la protection des droits d’auteur. Nous présentons un état de l’art de ces techniques, leurs apports et limites pour la protection des droits d’auteurs et les critères à respecter pour les besoins de cette application. Nous présentons également quelques exemples de logiciels de tatouage disponibles sur le Web.
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    Reversible data hiding scheme for the H.264/AVC codec
    (2013-06-24) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Very few reversible data hiding methods are proposed for compressed video and particularly for the H.264/AVC video codec, despite the importance of both of the watermarking reversibility criterion and the codec. The reversible watermarking techniques of images, when applied to the compressed video, can affect particularly the video quality and bitrate. Thus, to make these techniques applicable, the embedding capacity is usually reduced. Therefore an adaptation is necessary to improve the tradeoff between the embedding capacity, the visual quality and the bitrate of the watermarked video. In this paper, we investigate the possibility to introduce the DCT based reversible data hiding method, proposed initially for compressed images, to H.264/AVC codec. The embedding is applied during the encoding process, in the quantized DCT coefficients of I and P frames. To enhance the embedding capacity a mapping rule is used to embed three bits in one coefficient. Results show that exploiting the P frames improves considerably the video quality and the embedding capacity.
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    Reversible data hiding scheme for the H.264/AVC codec
    (CERIST, 2013) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Very few reversible data hiding methods are proposed for compressed video and particularly for the H.264 video codec despite the importance of both of the watermarking reversibility criterion and the codec. The reversible watermarking techniques of images, when applied to the compressed video, can affect particularly the video quality and bitrate. Thus, to make these techniques applicable, the embedding capacity is usually reduced. Therefore an adaptation is necessary to improve the tradeoff between the embedding capacity, the visual quality and the bitrate of the watermarked video. In this paper, we investigate the possibility to introduce the DCT based reversible data hiding method, proposed initially for compressed images, to H.264/AVC codec. The embedding is applied during the encoding process, in the quantized DCT coefficients in I and P frames. To enhance the embedding capacity a mapping rule is used to embed three bits in one coefficient. Results show that exploiting the P frames improves considerably the video quality and the embedding capacity.
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    Les services web sémantiques
    (CERIST, 2011-10) Boughacha, Rime; Bouchama, Samira; Aliane, Hassina; Makhzoumi, Dalila; Djeliout, Toufik
    Aujourd’hui, le web permet la connexion d’individus dans le monde entier et le partage des ressources et des connaissances dans différents domaines. Toutefois, la croissance et l’hétérogénéité des données contenues dans le web rendent le processus de recherche d’information difficile pour l’utilisateur humain. Le web sémantique pourrait jouer un rôle vital pour rendre explicite le contenu sémantique des ressources. Dans ce rapport, nous introduisons le domaine des services web sémantiques (SWS) qui a pour objectif d’intégrer les services web avec le web sémantique afin d'automatiser la découverte, l'invocation, la composition, et la surveillance des services web à travers le traitement des machines. A cet effet, nous présentons des notions sur les services web et leur rôle dans la transmission des données, en offrant une interopérabilité, et une gestion des liaisons entre les différentes applications. Des généralités sur le web sémantique et les ontologies sont également présentées et enfin, nous introduisons les services web sémantiques ainsi que quelques approches de découverte.
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    Le tatouage des images appliqué à l'imagerie médicale
    (Ecole nationale supérieure polytechnique, 2007) Bouchama, Samira; Berkani, D
    Le tatouage des images peut être défini comme étant une technique qui permet d'insérer des informations numériques dans une image de manière imperceptible et indélébile. En plus de son application initiale qui est la protection des droits d'auteur, le tatouage peut être utilisé dans d'autres domaines et en particulier dans le domaine de l'imagerie médicale pour contribuer à la sécurité des images partagées en réseau dans les applications de télémedecine. Dans ce mémoire nous étudions deux méthodes de tatouage, la première est basée sur la technique de communication CDMA (Accès Multiple par répartition de Code) et elle a pour objectif de vérifier l'authenticité d'une image. La deuxième fait appel à la cryptographie et à l'utilisation des bits les moins significatifs de l'image (LSBs) et elle a pour objectif de vérifier l'intégrité de l'image médicale et de garder la confidentialité des données du patient. Les tests sont effectués sur trois types d'images médicales, et les mesures de la qualité de l'image tatouée sont indispensables pour vérifier que la dégradation apportée par le tatouage ne conduit pas à un diagnostic erroné
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    Le tatouage des images pour l'intégrité et la confidentialité des données médicales
    (2008-04-21) Bouchama, Samira; Hamami, Latifa
    Dans cet article, nous présentons une méthode de tatouage appliquée au domaine de l’imagerie médicale que nous essayons d’adapter à la télémédecine. Cette méthode vise à insérer dans l’image médicale des informations de manière imperceptible dans le but de vérifier son intégrité et préserver la confidentialité des données du patient lors d’un partage en réseau. Cette méthode est basée sur l’utilisation des LSBs (les bits les moins significatifs) de l’image ainsi que des outils empruntés de la cryptographie.
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    Les techniques de tatouage appliquées à l’imagerie médicale
    (CERIST, 2008-10) Bouchama, Samira
    Les techniques de tatouage offrent une solution pour renforcer la sécurité des images médicales dans le cadre des applications de gestion des données médicales (HIS : Hospital Information System) et des applications de télémédecine. Dans ce travail nous présentons l’intérêt du tatouage pour l’imagerie médicale. Nous étudions et implémentons deux méthodes : La première a pour objectif de contrôler l’authenticité de l’image, quant à la deuxième, elle permet de vérifier son intégrité et préserver les données du patient. Ces méthodes sont testées sur trois types d’images médicales.
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    Les techniques de tatouage appliquées à l’imagerie médicale
    (2008) Bouchama, Samira; Hamami, Latifa
    Les techniques de tatouage offrent une solution pour renforcer la sécurité des images médicales dans le cadre des applications de gestion des données médicales (HIS : Hospital Information System) et des applications de télémédecine. Dans ce travail nous présentons l’intérêt du tatouage pour l’imagerie médicale. Nous étudions et implémentons deux méthodes : La première a pour objectif de contrôler l’authenticité de l’image, quant à la deuxième, elle permet de vérifier son intégrité et préserver les données du patient. Ces méthodes sont testées sur trois types d’images médicales.
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    Watermarking of compressed video based on DCT coefficients and watermark preprocessing
    (CERIST, 2010-12) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Considering the importance of watermarking of compressed video, several watermarking methods have been proposed for authentication, copyrights protection or simply for a secure data carrying through the Internet. Applied to the H.264/AVC video standard, in most of cases, these methods are based on the use of the quantized DCT coefficients often experimentally or randomly selected. In this paper, we introduce a watermarking method based on the DCT coefficients using two steps: the first one consists in a watermark pre-processing based on similarity measurement which can allow to adapt the best the watermark to the carrying coefficients of low frequencies. A second step takes advantage from the coefficients of high frequencies in order to maintain the video quality and reduce the bitrate. Results show that it is possible to achieve a very good compromise between video quality, embedding capacity and bitrate.
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    Watermarking of Compressed Video based on DCT Coefficients and Watermark Preprocessing
    (2011-03-05) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Considering the importance of watermarking of compressed video, several watermarking methods have been proposed for authentication, copyrights protection or simply for a secure data carrying through the Internet. Applied to the H.264/AVC video standard, in most of cases, these methods are based on the use of the quantized DCT coefficients often experimentally or randomly selected. In this paper, we introduce a watermarking method based on the DCT coefficients using two steps: the first one consists in a watermark pre-processing based on similarity measurement which can allow to adapt the best the watermark to the carrying coefficients of low frequencies. A second step takes advantage from the coefficients of high frequencies in order to maintain the video quality and reduce the bitrate. Results show that it is possible to achieve a very good compromise between video quality, embedding capacity and bitrate.