Recover the tampered image based on VQ indexing

Source: Signal Processing, Volume 90, Issue 1, Jan. 2010, pp. 331-343Authors: Chun-Wei Yang and Jau-Ji Shen Reporter: Te-Yu Chen(陳德祐 )

OutlineIntroductionThe Proposed Scheme

VQ Index Embedding and Watermark Embedding

Wong et al.’s Watermarking Schemes for Authentication and Ownership Verification

Watermark Extraction and Image recoveryExperimental ResultsConclusions & Comments

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Watermarking Data

Image Authentication with Tamper Detection and Recovery

Public channel

Embedding

Authenticate?

Yes

OK

No

Original image

Watermarked image Received image

Recovered image

Tamper recovery

3

4

Watermarking

Working DomainSpatial

Frequency

Robustness

Robust

Semi-Fragile

Fragile

PerceptionVisible

Invisible

Necessary Data for Extraction

Blind (Public)

Semi-Blind (Semi-Public)

Non-Blind (Private)

Requirements Ability of tamper detection Ability of tamper recovery Image quality Resistant to known attacks

Tamper watermarked image without being detected Counterfeit attack

Collage attack VQ attack

Blind attack Cropping

Trace out the mapping correlation of blocksThe four-scanning attack(brute-force/dictionary attack)

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Literature1. A Hierarchical Digital Watermarking Method for Image Tamper

Detection and Recovery Phen-Lan Lin, Chung-Kai Hsieh, and Po-Whei Huang, Pattern

Recognition, Vol. 38, Issue 11, 20052. A Majority-voting Based Watermarking Scheme for Color Image

Tamper Detection and Recovery Ming-Shi Wang and Wei-Che Chen, Computer Standards & Interfaces,

29, pp.561- 570, 20073. Dual Watermark for Tamper Detection and Recovery

Tien-You Lee and Shinfeng D. Lin, Pattern Recognition, 41(11), pp.3497-3506, 2008

4. Four-scanning attack on hierarchical digital watermarking method for image tamper detection and recovery

Chin-Chen Chang,Yi-Hsuan Fan, and Wei-Liang Tai, Pattern Recognition, Vol. 41, Issue 2, Feb. 2008, pp. 654-661

5. Watermarking for tamper detection and recovery Youngran Park, Hyunho Kang, Kazuhiko Yamahuchi, and Kingo

Kobayashi, IEICE Electronics Express, 5(17), pp. 689-696, 20086. Recover the tampered image based on VQ indexing

Chun-Wei Yang and Jau-Ji Shen, Signal Processing, 90(1), 2010, pp. 331-343

ComparisonsOurs Lin05 Wang07 Lee08 Park08 Yang10

Block size 2×2 4×4 2×2 2×2 4×4 -

Recovery granularity 2×2 2×2 2×2 2×2 2×2 -

Detection granularity 2×2 4×4 2×2 2×2 4×4 Coarse

Wmk embedding 3LSBs 2LSBs 3LSBs 3LSBs 2LSBs 3LSBs

Resistance to counterfeit attack Yes No No No No Yes

Resistance to blind attack Yes No No No No Yes

Resistance to four scanning attack Yes No No No No Yes

Resistance to collage attack Yes Yes Yes No No Yes

Resistance to cropping attack Yes Yes No No No Yes

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8

Watermarking

1 n32

1n3 2

The Proposed Scheme~ Embedding

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Recovery Information

Verification Information

Recovery information ~VQ Encoding

Index Table Original ImageCodebook

0123456‧‧‧

168‧‧‧

255

(150,135,…,128)

…

(20,65,…,110)

(90,135,…,120)(120,155,…,80)

(50,42,…,98)(49,117,…,25)

(100,125,…,150)

…

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168 120 11 250 36 58 12 3

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

11

10

10

168 120 11 250 36 58 12 3

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

Verification information ~ Wong’s watermarking scheme(Embedding)

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130 51

121 80

Image block

Hr = H(256, 256, 1016, 1, 130, 50, 120, 80) = 11010110…Fr = Hr Br = 1101 0100 = 1001⊕ ⊕Pr = Ek’(Fr) = Ek’(1001) = 0011

Watermarked block

Wong’s watermarking scheme~ Embedding

o 0 0 rH(M ,N ,I ,r,O )%

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NCHU NCHUNCHU NCHUNCHU NCHUNCHU NCHU

130 50

121 81

Original ImageMo: the image width (256)

No: the image height (256)

Io: the image ID (1015)

r: the block index (1)

the r-th image block after setting LSB1 to 0 (130, 50, 120, 80):o~r

Watermarked Image

The Proposed Scheme~ Tamper detection and recovery

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Detection

Recovery

Wong’s watermarking scheme~ Detection

15

16

10

10

Recovery information ~VQ Recovery

Recovered ImageCodebook

0123456‧‧‧

168‧‧‧

255

(150,135,…,128)

…

(20,65,…,110)

(90,135,…,120)(120,155,…,80)

(50,42,…,98)(49,117,…,25)

(100,125,…,150)

…

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Original Tampered(56% cropped)

Lee and Lin’s scheme PSNR=26.75dB

The proposed scheme PSNR=29.33dB

Experimental Results

Image size: 256×256 pixels CB size: 256 code words Code word:4×4 pixels IT can be embedded into O

four times

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CB size: 256×4×4×256 bits

Tampered

Recovered

Tampered

Recovered

PSNR=31.70dB 31.72dB 30.91dB 31.69dB

PSNR=31.28dB 31.99dB 30.33dB 31.72dB 19

35.24 dB 36.53 dB 31.11 dB

Tamped Image

Tamper detected images

The recovered images

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49% 61% 65% 70%

75% 80% 85% 90% 29.83dB 29.16dB 28.62dB 27.66dB

26.30dB 24.41dB 22.59dB 20.12dB 21

Conclusions An image tamper detection and recovery scheme

integrating Wong’s watermarking scheme and VQ is proposed.

The number of times of embedding the recovery info. into the image is adjustable.

The quality of the recovered image is high. Resistant against the known attacks. (Wong et

al.’s scheme is adopted)

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Comments Owing to the use of a public key cryptographic

system, the block size should be large enough for the security concern(1024bits). However, the larger the block size is, the less precision of error detection will be.

Owing to the use of a public key cryptographic system, the computational cost is high.

Additional cost: code book(4×4 ×256×256 bits)

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