Source: Signal Processing, Vol. 89, Issue 6, June 2009, Pages Author: Piyu Tsai, Yu-Chen Hu, and Hsui-Lien Yeh Speaker: Hon-Hang Chang Date:
Outline Introduction Related Work Proposed Method Experiment Results Conclusions
Introduction Reversible data hiding Original image Stego-image Secret data Original image Extract Embed
Related work The histogram-based reversible data hiding 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
Proposed method Linear prediction Original image (block size 5 by 5) Basic pixel Residual image Non-negative histogram (NNH) Negative histogram (NH) Peak value: -3 Zero value: -1 Peak value: 1 Zero value: 3
Proposed method(Cont.) Linear prediction Non-negative histogram (NNH) Negative histogram (NH) Peak value= -3 Zero vale= -1 Peak value= 1 Zero vale= Residual image Embed area
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) Embed area Residual image Peak value= -3 Zero vale= -1 Peak value= 1 Zero vale= 3 b = … … Stego-image
Proposed method(Cont.) Extracting Peak value= -3 Zero vale= -1 NH Peak value= 1 Zero vale= 3 NNH Stego-imageResidual stego-image or -3 b=1 no change 2 or -2 b=0 return to the peak pixel (1 or -3) b = … … 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 Original image (block size 5 by 5)
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) Residual image b= Residual image
Experiment results Fig. 1 Testing image ‘‘MRI_400_400’’: (a) original image, (b) original histogram, (c) residual histogram and (d) stego-image.
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
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.