increasing watermarking robustness using turbo codes
DESCRIPTION
Increasing Watermarking Robustness using Turbo Codes. Corina Nafornita, Alexandru Isar , Maria Kovaci Politehnica University of Timisoara Email: {corina.nafornita, alexandru.isar, [email protected]}. Robustness. Capacity. Imperceptibility. Goal. Duo-binary turbo codes. - PowerPoint PPT PresentationTRANSCRIPT
WISP 2009, Budapest, Hungary
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Increasing Watermarking Robustness using Turbo Codes
Corina Nafornita, Alexandru Isar, Maria Kovaci
Politehnica University of TimisoaraEmail: {corina.nafornita, alexandru.isar,
WISP 2009, Budapest, Hungary
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Goal
Imperceptibility
Robustness
Capacity
Duo-binary turbo codes
Perceptual mask - DWT
Watermarking requirements
WISP 2009, Budapest, Hungary
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Barni et al., 2001
Daubechies-6
Mask
Watermark
Original Marked
DWTIDWT
WISP 2009, Budapest, Hungary
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Artifacts low resolution mask High resolution mask
Watermark easily erased All resolution levels
New approach: duo-binary turbo codes
Proposed solution
WISP 2009, Budapest, Hungary
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New method
Bior2.2
New mask
Encoded Watermark
Original Marked
DWTIDWT
DBTC message
Select only higher coefficients!!!
WISP 2009, Budapest, Hungary
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Mask estimation
Low resolution vs. High resolution (Barni et al.,2001) (Nafornita et al.,2006)
WISP 2009, Budapest, Hungary
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Duo-Binary Turbo Code
8-state duo binary RSC encoder , rate 2/3. Encoder polynomials: 15 (feedback) and 13
(redundancy)
RSC r-ary
RSC r-ary
ilv
Input sequence
ru
1
1
c1
c2
u2
1
c =u0
11
S1
u1 u1
u2
S3S2
0
11 01
,d i j i j i j S
WISP 2009, Budapest, Hungary
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Experiments
Lena•Test image Lena
•Message length: 768 bits
•Block size 7
•Threshold 10
•Watermark strength =9
•PSNR obtained 29.95 dB Watermarked Lena
WISP 2009, Budapest, Hungary
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AWGN: σ=3.25…15
BER vs. BER vs. PSNR
WISP 2009, Budapest, Hungary
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JPEG compression: Q=10…100
BER vs. quality factor
BER vs. PSNR
WISP 2009, Budapest, Hungary
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Coded vs. Uncoded
Attack vs. BERBER
Uncoded DBTC
JPEG compression, Q=50, PSNR=32.94 dB
0.167132 0.001488
AWGN, =8, PSNR=29.29 dB
0.0885 3.25·10-4
WISP 2009, Budapest, Hungary
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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