Digital Watermarking Using Digital Watermarking Using Phase Dispersion --- Update Phase Dispersion --- Update SIMG 786 SIMG 786 Advanced Digital Image Advanced Digital Image Processing Processing Mahdi Nezamabadi, Mahdi Nezamabadi, Chengmeng Liu, Chengmeng Liu, Michael Su Michael Su
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Digital Watermarking Using Phase Dispersion --- Update SIMG 786 Advanced Digital Image Processing Mahdi Nezamabadi, Chengmeng Liu, Michael Su.
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Digital Watermarking Using Phase Digital Watermarking Using Phase Dispersion --- UpdateDispersion --- Update
SIMG 786 SIMG 786
Advanced Digital Image ProcessingAdvanced Digital Image Processing
Mahdi Nezamabadi, Mahdi Nezamabadi,
Chengmeng Liu, Chengmeng Liu,
Michael SuMichael Su
OutlineOutline
• Carrier design
• Embedding and extraction for single tile and Multi-tiles (improving the robustness)
• Parameter α selection and invisibility
• Moment Normalization• Rotation/Scale Detection
Carrier Implementation 1Carrier Implementation 1
• Carrier is implemented in frequency domain
• Carrier has random phase
• The amplitude of Carrier is high pass in order to make it invisible in spatial domain
• Carrier should be symmetric in frequency domain in order to make its imaginary part to 0 in spatial domain
Carrier Implementation 2Carrier Implementation 2High-pass vs. All-passHigh-pass vs. All-pass
Carrier Implementation 3Carrier Implementation 3
• Auto correlation of Carrier function should approximate delta function
• The average of Carrier should be 0
Carrier Implementation 4Carrier Implementation 4if Carrier is not symmetric in frequency domainif Carrier is not symmetric in frequency domain
Embedded MessageEmbedded Message
*• Convolution is
implemented by multiplication of Fourier transform in frequency domain
• Zero padding must be performed before FFT
Tiling Improves the RobustnessTiling Improves the Robustness
Tiling Improves the RobustnessTiling Improves the Robustness
• After 8 by 8 tiling, the summation of tiles is shown at right
• The amplitude of the input image will be averaged to flatten after summation of 64 tiles