Theses and Dissertations

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    hybrid approach to digital image watermarking using informed coding, informed embedding and spread spectrum
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2006) Dey, Nayan Kumar; Mitra, Suman K.; Jadhav, Ashish
    The growth and popularity of the Internet has led to the data storage of multimedia data (audio, image and video) in digital form. The digitization form of multimedia data can be copied easily and then distributed again without the loss of fidelity. This leads to wide interest in multimedia security and multimedia copyright protection. Digital watermarking appears today as an efficient mean of securing and protecting multimedia data. It embeds a data called watermark into multimedia data such that watermark can be detected or extracted later to make an assertion about the multimedia data. In this report, we proposed a noble hybrid watermarking scheme joining informed coding and informed embedding approach to with the most utilized spread spectrum techniques. In informed coding, the codeword used to represent a message is dependent on the cover work in which message is embedded. In informed embedding, the embedding process tailors each watermark patterns according to cover work. Our informed coding is based on trellis, which is modified so that each message can be represented by set of alternative vectors. Our scheme first embeds a watermark using informed coding and informed embedding and to increase the robustness, another spread spectrum based watermark is embedded. The watermark added to our algorithm is perceptually invisible in nature. The effectiveness of this scheme is verified through series of experiments, in which a number of standard image processing attacks are conducted. The obtained results demonstrate, proposed algorithm survives a wide range of attacks.
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    ItemOpen Access
    Multiple watermarking schemes for copyright protection
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2005) Bhatt, Krutarth; Mitra, Suman K.
    Recent advances in digital communication and storage technologies have brought major changes for consumers. High capacity hard disks and DVDs can store a huge amount of audiovisual data. In addition, faster Internet connection speeds and emerging high bit rate DSL connection provide sufficient bandwidth for entertainment networks. These improvements in computer networks and communication technology are changing the economies of intellectual property reproduction and distribution. Intellectual property owners must exploit the new ways reproducing, distributing, and marketing their intellectual property. However a major problem with current digital distribution is the great threat of piracy. Digital watermarking is proposed as a solution to avoid digital piracy.

    In this work we have addressed multiple watermarking to increase robustness requirement for copyright protection and ownership prevention. Taking into account the scenarios for the present content distribution environment, we do rely on sending and distributing the content through physical channels along with digital network communication and distribution. We may publish the content in some newspapers and/or magazines etc. According to our belief there are very few techniques that are highly robust against unintentional image processing like print-scan, dithering that are routinely performed during publication of an image along with the conventional attacks that are performed on digital representation of an image. We have developed two techniques; one is “Multiple Watermarking using feature selection” and the other is “Multiple Watermarking in Hybrid SVD-DCT domain”. Both the techniques are highly robust against various attacks including JPEG-Lossy compression, Blurring, Median filtering, Rotation, Cropping, Scaling, Rescaling, Histogram Equalization, Intensity Adjustment, Gamma Correction, Gaussian Noise Addition, Salt & Pepper Noise Addition, Uniform Noise Addition, Dithering, Print & Rescan, Intentional Tampering, Pixelate etc. Imperceptibility, Security and Reliability of Detection are also satisfied by the proposed techniques.