A hierarchical digital watermarking method for image tamper detection and recovery
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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, December 2005, pp. 2519-2529. Outline. Introduction The Proposed Method Watermark Embedding

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A Hierarchical Digital Watermarking Method for Image Tamper Detection and Recovery

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A hierarchical digital watermarking method for image tamper detection and recovery

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, December 2005, pp. 2519-2529


Outline

Outline

  • Introduction

  • The Proposed Method

    • Watermark Embedding

    • Hierarchical Tamper Detection

    • Tampered Image Recovery

  • Experimental Results

  • Conclusions

  • Comments


Introduction

Introduction

  • Watermarking Method for Image Tamper Detection and Recovery


Block mapping sequence generation algorithm 4 4 pixels block

Block mapping sequence generation algorithm (4 ×4 pixels/block)

  • 1-1 mapping : X ' = [ f ( X ) = ( k × X ) mod N ] + 1,

  • X , X ' are the block number (∈ [0, N− 1 ])

  • k is a secret key, (a prime and ∈ Z − {N 's factors })

  • N is the total number of blocks in the image

The original block

The mapping of blocks

X '=13×X mod 64 +1


Watermark embedding 1 2

r

Watermark Embedding (1/2)

avg_As=(I1+I2+I3+I4)/4

avg_Bs=(I1+I2+I3+I4)/4

Block A

avg_B=(I1+I2+…+I16)/16

Block B


Watermark embedding 2 2

Watermark Embedding (2/2)

Block A

num: # of 1s in the 6 MSBs of avg_Bs

avg_As=(69+78+35+46)/4=57=(00111001)2

r = 001110

Block B

avg_Bs=(104+20+36+52)/4=53=(00110101)2

avg_B=(104+20+96+204+…+164)/16=97

v=0, p=1

104

104

Set 2LSBs to 0

22

22

39

39

55

54


Hierarchical tamper detection 1 3

Hierarchical Tamper Detection (1/3)

Level 1: for each sub-block B's of 2×2 pixels within block B' , verify v and p

avg_B’s=(104+20+36+52)/4=53=00110101

avg_B’=(104+20+96+204+…+164)/16=97

v'=0, p'=1

ifv'is not equal to v

OR if p'is not equal to p

 This sub-Block is marked erroneous

v=0, p=1

After Level 1 detection, each sub-block is marked valid of erroneous


Hierarchical tamper detection 2 3

Hierarchical Tamper Detection (2/3)

Level 2: For each block of size 4 × 4 pixels, mark this block erroneous if any of its sub-block is marked erroneous; otherwise, mark it valid.

After Level 2 detection, each block is marked valid of erroneous

Level 3: For each valid block of size 4×4 pixels, mark the block erroneous if there are five or more erroneous blocks in its 3×3 block-neighborhood,

Most surrounding blocks of some valid block are erroneous,

this block hardly remains valid.


Hierarchical tamper detection 3 3

Hierarchical Tamper Detection (3/3)

Level 4: only required for resisting against VQ attack,

assume mapping sequence:B C

valid

Block C

r = 001110(00) = 56 = avg_Cs

avg_B’s=(68+76+32+44)/4=55

valid

57=00111001=00111000=56

avg_B’s avg_Cs

Block B’


Tampered image recovery

Tampered Image Recovery

Mapping sequence: A B

valid

Block B

r = 001110(00) = 56

erroneous

Tamped Block A

Recovered Block A


Experimental results 1 7

Experimental Results (1/7)


Experimental results 2 7

Experimental Results (2/7)


Experimental results 3 7

Experimental Results (3/7)

  • M1: Covering the whole image with leaf patterns, as depicted in Fig. 8(b).

  • M2: Covering the whole image with another image, as depicted in Fig. 8(c).

  • M3: Covering the whole image with fruit patterns, as depicted in Fig. 8(d).

  • M4: Spreading plenty of mist to the whole image, as depicted in Fig. 8(e).


Experimental results 4 7

Experimental Results (4/7)


Experimental results 5 7

Experimental Results (5/7)


Experimental results 6 7

Experimental Results (6/7)


Experimental results 7 7

Experimental Results (7/7)


Conclusions

Conclusions

  • A hierarchical digital watermarking scheme for image tamper detection and restoration is proposed.

  • The proposed method uses parity check and intensity comparison with 3-Level detection for tamper detection.

  • The proposed method uses 2-LSBs of each pixel to restore the check bits and restore information.


Comments

Comments

  • Level 4 detection resists against VQ attack (collage attack)

  • Something is wrong withLevel 4 detection

  • Reversible watermarking such as DE or histogram shifting is not suitable for tamper detection and recovery, this is because the bit-rate is low.


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