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A hierarchical digital watermarking method for image tamper detection and recovery. Source: Pattern Recognition, Vol. 38, Issue 11, December 2005, pp. 2519-2529 Author: Phen-Lan Lin, Chung-Kai Hsieh, Po-Whei Huang Speaker: Yi-Hsuan Fan Date: 2005/10/06. Outline. Introduction
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A hierarchical digital watermarking method for image tamper detection and recovery Source: Pattern Recognition, Vol. 38, Issue 11, December 2005, pp. 2519-2529 Author: Phen-Lan Lin, Chung-Kai Hsieh, Po-Whei Huang Speaker: Yi-Hsuan Fan Date: 2005/10/06
Outline • Introduction • Proposed method • Preparation • Watermark embedding • Hierarchical tamper detection • Tampered image recovery • Experimental results • Conclusion
Introduction delivered image received image
Preparation Torus automorphism block 1 mapping sequence : 1, …, 3, …, 10, …, 1
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) Example : avg_As=(69+78+35+46)/4=57=00111001 r=001110 avg_Bs=(104+20+36+52)/4=53=00110101 avg_B=(104+20+96+204+…+164)/16=97 v=0, p=0 block A 104 104 22 20 39 39 55 54 block B
Hierarchical tamper detection (1/2) Level 1 : avg_Bs=(104+20+36+52)/4=53=00110101 avg_B=(104+20+96+204+…+164)/16=97 v’=0, p’=0 v=0, p=0 Level 2 : Level 3 :
Hierarchical tamper detection (2/2) Level 4 : block B r=001110(00)=56=avg_Bs avg_As=(69+78+35+46)/4=57 57=00111001=00111000=56 avg_Bs avg_As block A
Tampered image recovery block B r=001110(00)=56 tamped block A recovered block A
Conclusion • A efficient and effective digital watermarking method for image tamper detection and recovery.