International Conference Papers

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Author: search.filters.author.Bouchama, SamiraHas files: Yes

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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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    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
    (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 techniques applied to H264/AVC video standard
    (2010-04-21) Bouchama, Samira; Hamami, Latifa; Aliane, Hassina
    Video watermarking describes the process of embedding information in video to satisfy applications such as the protection of intellectual property and the control of video authentication. In this field, researchers orient their investigations towards the new video standard H264/AVC which is increasingly used because of the coding efficiency it provides comparing to the previous standards. The different modules of this standard are exploited to embed watermark while responding to the application demands in terms of fragility or robustness to certain attacks and in terms of maintaining video quality and video bit rate. The aim of this paper is to give a global vision on the H264/AVC and to present some robust and fragile watermarking techniques applied to this video standard.
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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.
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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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    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