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Improving histogram-based reversible data hiding by interleaving predictive. Source: IET Image Processing, Vol . 4, No. 4, Aug. 2010, pp.223-234 Authors : C.-H. Yang and M.-H. Tsai Speaker : Hon-Hang Chang Date : 2010/12/01. Outline. Introduction Related work Proposed method
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Improving histogram-based reversible data hiding by interleaving predictive Source: IET Image Processing, Vol. 4, No. 4, Aug. 2010, pp.223-234 Authors : C.-H. Yang and M.-H. Tsai Speaker : Hon-Hang Chang Date : 2010/12/01
Outline • Introduction • Related work • Proposed method • Experiment results • Conclusion
Histogram Introduction - = Difference Array D Cover image Predicted image + = Predicted image Stego-image Difference Array D’ Embed the secret bit 0 or 1
Related work S= 0110 • Lin et al.’s method Shift Embed D D D H Shift Stego-image
Related work (Cont.) S= 0110 • Lin et al.’s method Extract Shift D D D Stego-image Shift H
Proposed method • Embedding in odd columns D1,1=H1,1-H1,2=5-5=0 D1,3=H1,3- ˻(H1,2+H1,4)/2˼ =5- 4= 1 D1,3=H1,5- H1,4 =4- 4= 0 H D Odd columns (Predicted pixels) Even columns(Sample pixels) D’s Histogram
Proposed method(Cont.) • Embedding in odd columns Podd1=0 Podd2=-1 Zodd1=2 Podd2=-3 D D’s Histogram Shift Shift D D’s Histogram after shifting
Proposed method(Cont.) • Embedding in odd columns Embed secret bit 0, no change!! Secret bits I: 01110011001 W1,1=W1,2+D1,1=5+0=5 W1,3=˻(W1,2+W1,4)/2˼+D1,3=4+2=6 W1,5=W1,4+D1,5=4+1=5 D’s Histogram after shifting Embed secret bit 1, changed toPodd2-1or Podd1+1!! Embed Stego-image W1 D D
Proposed method(Cont.) • Embedding in even columns D1,2=H1,2- ˻(H1,1+H1,3)/2˼ =5- 5= 0 D1,4=H1,4- ˻(H1,3+H1,5)/2˼ =4-5=-1 W1 D Odd columns (Sample pixels ) Even columns(Predicted pixels) D’s Histogram
Proposed method(Cont.) • Embedding in even columns Shift Shift Podd1=2 Podd2=-1 Zodd1=4 Zodd2=-3 D D’s Histogram D D’s Histogram after shifting
Proposed method(Cont.) • Embedding in even columns Embed secret bit 0, no change!! Secret bits II: 01101 W1,2=˻(W1,1+W1,3)/2˼+D1,2=5+0=5 W1,4=˻(W1,3+W1,5)/2˼+D1,4 =5+(-1)=4 D’s Histogram after shifting Embed secret bit 1, changed toPodd2-1or Podd1+1!! Embed Stego-image W2 D D
Proposed method(Cont.) D1,2= W1,2 -˻(W1,1+W1,3)/2˼ =5-5=0 D1,4= W1,4 -˻(W1,3+W1,5)/2˼ =4-5=-1 • Extracting in even columns Podd1=2 Podd2=-1 D’s Histogram Zodd1=4 Zodd2=-3 Stego-image W2 D D’s Histogram D Secret bits II: 01101 Stego-image W1
Proposed method(Cont.) D1,1=W1,1-W1,2=5-5=0 D1,3= W1,3 -˻(W1,2+W1,4)/2˼=6-4=2 D1,5=W1,5-W1,4=5-4=1 • Extracting in odd columns Podd1=0 Podd2=-1 D’s Histogram Zodd1=2 Zodd2=-3 D Stego-image W1 D H D’s Histogram Secret bits I: 01110011001
Proposed method(Cont.) • Other predictive methods Figure 1 Chessboard with white pixels and black pixels
Experiment results Tabel 1 Compassion between the Lin’s method [4], Lin’smethod [5], Hsiao’s method [8] and our schemes with thechessboard interleaving prediction
Experiment results Table 2 Comparison of capacity, shifting numbers, changing numbers and PSNR values
Conclusion • The proposed method achieve the larger capacity, • but also keep the image quality better.