1. Source: Signal Processing, Vol. 89, Issue 6, June 2009, Pages 1129-1143 Author: Piyu Tsai, Yu-Chen Hu, and Hsui-Lien Yeh Speaker: Hon-Hang Chang Date: 2010.09.14

2. Outline Introduction Related Work Proposed Method Experiment Results Conclusions

3. Introduction Reversible data hiding Original image Stego-image Secret data Original image Extract Embed

4. Related work The histogram-based reversible data hiding 56667 55666 33550 12222 12331 46567 44655 33440 12222 12331 original image stego image Peak value: 6 Zero value: 4 b= 1, no change b=0, close to zero pixel at 1 Peak value (Embeddable) In the range from zero value to peak value Close to zero value at 1 Out of the range from zero value to peak value No change b=101100

5. Proposed method Linear prediction 56667 55666 33550 12222 12331 Original image (block size 5 by 5) Basic pixel 01112 00111 -2 50-5 -4-3 -4-3-2 -4 Residual image Non-negative histogram (NNH) Negative histogram (NH) Peak value: -3 Zero value: -1 Peak value: 1 Zero value: 3

6. Proposed method(Cont.) Linear prediction Non-negative histogram (NNH) Negative histogram (NH) Peak value= -3 Zero vale= -1 Peak value= 1 Zero vale= 3 +1 01112 00111 -2 50-5 -4-3 -4-3-2 -4 Residual image 3 5 03 00 50-5 -4 -4 Embed area

7. Proposed method(Cont.) Embedding Rule: b=1, no change (-3 or 1) b=0, the peak pixel close to zero pixel at 1 (-2 or 2) 01213 00122 50-5 -4-3-2-3-2 -4-3 -4 Embed area 01112 00111 -2 50-5 -4-3 -4-3-2 -4 Residual image Peak value= -3 Zero vale= -1 Peak value= 1 Zero vale= 3 b = …1 0 1 1 0 0 1 0 1 0 1… 56768 55677 44550 12323 12441 Stego-image

8. Proposed method(Cont.) Extracting 56768 55677 44550 12323 12441 Peak value= -3 Zero vale= -1 NH Peak value= 1 Zero vale= 3 NNH Stego-imageResidual stego-image 01213 00122 50-5 -4-3-2-3-2 -4-3 -4 1 or -3  b=1  no change 2 or -2  b=0  return to the peak pixel (1 or -3) b = …1 0 1 1 0 0 1 0 1 0 1… 01112 00111 -2 50-5 -4-3 -4-3-2 -4 The pixel x in the range from zeros value and peak value : Close toward the peak value at 1 The pixel x out of the range from zeros value and peak value : no change 56667 55666 33550 12222 12331 Original image (block size 5 by 5)

9. Proposed method  Overlapping scheme Peak value= 1, 0 Zero vale= 3, 4 NNH b= 1, no change b=0, close to zero pixel at 1 Peak value (Embeddable) b= 1close to zero pixel at 1 b=0, close to zero pixel at 2 Overlap value (Embeddable) Close to the zero pixel at 2 Peak value (No embed) 01112 00111 -2 50-5 -4-3 -4-3-2 -4 Residual image b=1 1 0 0 1 0 1 0 0 0 02332 01233 -2 51-5 -4-3 -4-3-2 -4 Residual image

10. Experiment results Fig. 1 Testing image ‘‘MRI_400_400’’: (a) original image, (b) original histogram, (c) residual histogram and (d) stego-image.

11. Experiment results(Cont.) Fig. 1 Testing image ‘‘MRI_400_400’’: (a) original image, (b) original histogram, (c) residual histogram and (d) stego-image. Fig. 2. Relationship between the stego-image quality and the hiding capacities

12. Conclusions  The proposed method can achieve the goal of higher hiding capacity.  The secret data are embedded in the residual images instead of the image histogram.