Increasing Watermarking Robustness using Turbo Codes

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Increasing Watermarking Robustness using Turbo
Codes

• Corina Nafornita, Alexandru Isar, Maria Kovaci
• Politehnica University of Timisoara
• Email corina.nafornita, alexandru.isar,
  maria.kovaci_at_etc.upt.ro

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Goal
Duo-binary turbo codes
Watermarking requirements
Perceptual mask - DWT
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Barni et al., 2001

• Daubechies-6

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Proposed solution

• Artifacts ?? low resolution mask
• High resolution mask
• Watermark easily erased
• All resolution levels
• New approach duo-binary turbo codes

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New method
DBTC
message

• Bior2.2

Select only higher coefficients!!!
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Mask estimation

• Low resolution vs. High resolution
• (Barni et al.,2001) (Nafornita et
  al.,2006)

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Duo-Binary Turbo Code

• 8-state duo binary RSC encoder , rate 2/3.
• Encoder polynomials 15 (feedback) and 13
  (redundancy)

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Experiments

• Test image Lena
• Message length 768 bits
• Block size 7
• Threshold 10
• Watermark strength ?9
• PSNR obtained 29.95 dB

Lena
Watermarked Lena
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AWGN s3.2515
BER vs. ?
BER vs. PSNR
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JPEG compression Q10100
BER vs. quality factor
BER vs. PSNR
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Coded vs. Uncoded
Attack vs. BER BER BER
Attack vs. BER Uncoded DBTC
JPEG compression, Q50, PSNR32.94 dB 0.167132 0.001488
AWGN, ?8, PSNR29.29 dB 0.0885 3.2510-4
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Conclusions

• BER decreases in both cases when using turbo
  codes
• Less severe attacks
• perfect reconstruction,
• the attack modeled like an AWGN channel with high
  SNR.
• Coding gain of DBTC higher than 2 dB