Top Banner

of 22

Digital Watermarking Using Phase Dispersion --- Update SIMG 786 Advanced Digital Image Processing Mahdi Nezamabadi, Chengmeng Liu, Michael Su

Jan 21, 2016



  • Digital Watermarking Using Phase Dispersion --- UpdateSIMG 786 Advanced Digital Image ProcessingMahdi Nezamabadi, Chengmeng Liu, Michael Su

  • OutlineCarrier designEmbedding and extraction for single tile and Multi-tiles (improving the robustness)Parameter selection and invisibility Moment NormalizationRotation/Scale Detection

  • Carrier Implementation 1Carrier is implemented in frequency domainCarrier has random phaseThe amplitude of Carrier is high pass in order to make it invisible in spatial domainCarrier should be symmetric in frequency domain in order to make its imaginary part to 0 in spatial domain

  • Carrier Implementation 2High-pass vs. All-pass

  • Carrier Implementation 3Auto correlation of Carrier function should approximate delta functionThe average of Carrier should be 0

  • Carrier Implementation 4if Carrier is not symmetric in frequency domain

  • Embedded Message*Convolution is implemented by multiplication of Fourier transform in frequency domainZero padding must be performed before FFT

  • Tiling Improves the Robustness

  • Tiling Improves the RobustnessAfter 8 by 8 tiling, the summation of tiles is shown at rightThe amplitude of the input image will be averaged to flatten after summation of 64 tilesThe watermark information is amplified

  • Parameter = 0.1 = 0.05 = 0.1 = 0.3 = 0.5 = 0.7

  • Parameter = 0.3 = 0.05 = 0.1 = 0.3 = 0.5 = 0.7

  • Parameter = 0.5 = 0.05 = 0.1 = 0.3 = 0.5 = 0.7

  • Parameter = 0.7 = 0.05 = 0.1 = 0.3 = 0.5 = 0.7

  • Similarity vs. Similarity is measured by cross correlation between original and extracted log64 tiles were used in embeddingThe controls the visibility of the watermark logo in the watermarked imageThe also depends on the number of tiles

  • Attacked by low pass filterThe watermarked image is blurred The extracted logo is equivalent to original log convolve with a low pass filter=0.3,no blurred=0.3,blurred

  • Moment NormalizationPreprocessing to remove the high amplitude, low frequency noiseAt flat area, v is replaced by random number with variance of d

  • Rotation/Scale DetectionThreshold and image Dilation

  • Rotation/Scale DetectionImage rotation

  • Rotation/Scale DetectionImage rotation

  • Current Issues and ProblemsOdd and Even dimensions of Carrier function generate different output result in spatial domain.

    How to deal with interpolation errors during rescaling and re-rotation processes

  • Follow-up WorksImplement Contrast Sensitivity Function in Carrier function designRotation/Scale pattern detection Rotate back to right orientation and scale back to its original dimensionsImplementation of Binary Message template functionIntegrate all functions and final presentation and report

  • Thank You!