Fraunhofer Institut für Integrierte Publikations-und Informationssysteme IPSI

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  • Publication
    Using entropy for image and video authentication watermarks
    ( 2006)
    Thiemert, S.
    ;
    Sahbi, H.
    ;
    Steinebach, M.
    There are several scenarios where the integrity of digital images and videos has to be verified. Examples can be found in videos captured by surveillance cameras. In this paper we propose a semi-fragile watermarking scheme, which can be applied on still images as well as on digital videos. We concentrate on the protection of I-frames in compressed MPEG-1/2 videos. We use the entropy of the probability distribution of gray level values in block groups to generate a binary feature mask, which is embedded robustly into an adjacent I-frame. The approach can distinguish between content-preserving and content-changing manipulations. Positions of content-changing manipulations can be localized. We provide experimental results to analyze the effectiveness of the scheme. In the evaluation part we concentrate on the robustness against content-preserving and the sensitivity to content-changing manipulations.
  • Publication
    Applying interest operators in semi-fragile video watermarking
    ( 2005)
    Thiemert, S.
    ;
    Sahbi, H.
    ;
    Steinebach, M.
    In this article we present a semi-fragile watermarking scheme for authenticating intra-coded frames in compressed digital videos. The scheme provides the detection of content-changing manipulations while being moderately robust against content-preserving manipulations. We describe a watermarking method based on invariant features referred to as interest points. The features are extracted using the Moravec-Operator. Out of the interest points we generate a binary feature mask, which is embedded robustly as watermark into the video. In the verification process we compare the detected watermark with the interest points from the video to be verified. We present test results evaluating the robustness against content-preserving manipulations and the fragility in terms of content-changing manipulations. Beside the discussion of the results we propose a procedure to provide security of the scheme against forgery attacks.