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Invisible Watermark

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Invisible Watermark. By Elo Leung and Wing Wong CS 265 Section 2 Spring 2004. Table of Contents. Project Objectives Watermarking in General Attacks on Watermarks Desired Characteristics of Invisible Watermarks Spread Spectrum Watermarking – Insert & Extract Watermark Example - PowerPoint PPT Presentation
  • By Elo Leung and Wing WongCS 265 Section 2Spring 2004

  • Table of ContentsProject ObjectivesWatermarking in GeneralAttacks on WatermarksDesired Characteristics of Invisible WatermarksSpread Spectrum Watermarking Insert & Extract WatermarkExampleAdvantages & Disadvantages8. Conclusion

  • Project Objectives Analyze the spread spectrum watermarking algorithm proposed by Cox et al.

    Demonstrate the application of Coxs algorithm using a sample image file

  • Watermarking in Generalthe 3 components:


    Encoder watermark insertion

    Decoder and Comparator watermark extraction and verification

  • Watermarking in Generalthe 3 components:WatermarkEncoderDecoder and ComparatorFigure provided by Mohanty [2].

  • Watermarking in GeneralUses 3 components:WatermarkEncoderDecoder and ComparatorFigure provided by Mohanty [2].

  • Attacks on WatermarkFigure provided by Cox et al. [1].

  • Attacks on Watermark

  • Attacks on WatermarkSpecific for images/videosrotation, translation, scaling, and cropping operations

  • Attacks on Watermark

  • Attacks on WatermarkRewatermarking

  • Desired Characteristics of Invisible WatermarksPerceptually unnoticeable

    Robust to common watermark attacks

    Quality degradation upon removal of watermarks

    Unambiguously identifies the owner of the digitized medium (audio, video, or image).

  • Spread Spectrum WatermarkingSpread Spectrum Watermark = Invisible Watermark

    Key: Insert watermark at perceptually significant regions

    Spread watermark throughout the data

    **Data = audio, video, or image file

  • Spread Spectrum WatermarkingInsertion ProcessFigure provided by Mohanty [2].v'i = vi (1 + xi)

  • Spread Spectrum WatermarkingExtraction ProcessFigure provided by Mohanty [2].

  • Example(1) Original (2) Watermarked Differences of (1) & (2)

  • Advantages & DisadvantagesAdvantages: Not noticeable since the watermarks are spread out.

    Cant be removed without severe quality degradation since watermarks are inserted at perceptually significant regions.Disadvantages:

    Original watermark is required in the extraction process.

  • ConclusionSpread spectrum watermarking:

    Can be used for audio, video, and image files

    Meets the desired characteristics of invisiblewatermarks unnoticeable, robust, unambiguous

  • References:[1]Ingemar J. Cox, et al., Secure Spread Spectrum Watermarking for Multimedia, IEEE Trans. on Image Processing, Vol. 6, No.12, Dec 1997, pp.1673-1687. [2] Saraju P. Mohanty, Digital Watermarking: A Tutorial Review, Department of Computer Science and Engineering, University of South Florida.[3] Peter Meerwald, Digital Image Watermarking in the Wavelet Transform Domain, Masters Thesis, Department of Scientific Computing, University of Salzburg, Austria, January 2001.

    [4] http://www.cosy.sbg.ac.at/~pmeerw/Watermarking/source/

  • The End

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