Reversible Image Watermarking Using Interpolation Technique Source: IEEE Transcation on Information Forensics and Security, Vol. 5, No. 1, March 2010 Authors: Lixin Luo, Zhenyong Chen, Ming Chen, Xiao Zeng and Zhang Xiong Speaker: Hon- Hang Chang Date:

Outline  Introduction  Proposed Method  Experiment Results  Conclusions 2

Introduction 3 Embed Cover image Watermark Watermarked image Watermark Cover image Watermarked image Extract

Proposed Method(Cont.) 4 LSB replacement LM, LN RM, RN Boundary Map Overhead  LSB replacement of the overhead information Marginal area of cover-image Cover image

●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● Proposed Method(Con.t) 5  Interpolation in Non-Sample pixels ● Sample pixel ○ Non-Sample pixel ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● Cover image X ○ The Non-Sample pixel after predicting 1-Level 2-Level

●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● ○○○○○○○ ●○●○●○● Proposed Method(Cont.) 6  Interpolation in Sample pixels ● Sample pixel ○ Non-Sample pixel ○ The Non-Sample pixel after predicting●○●○●○●○○○○○○○ ●○○○○○● ○○○○○○○ ●○○○○○● ○○○○○○○ ●○●○●○● 3-Level

Proposed Method(Cont.) 7  Interpolation in Non-Sample pixels (1/2) S 45 = {60, 52,40} Cover image X Mean 45 =(S 45 (1)+S 45 (3))/2 =(60+40)/2 =50 Mean 135 =(S 135 (1)+S 135 (3))/2 =(30+50)/2 =40 S 135 ={30, 52,50} Interpolation X ’ u= ( Mean 45 + Mean 135 )/ 2 = (50+40)/2 = 45

Proposed Method 8  Interpolation in Non-Sample pixels (2/2) S 0 = {30, 18,40} Cover image X S 90 ={52, 18,45} Interpolation X ’ Mean 0 =(S 0 (1)+S 0 (3))/2 =(30+40)/2 =35 Mean 90 =(S 90 (1)+S 90 (3))/2 =(52+45)/2 =48.5 u= ( Mean 0 + Mean 90 )/ 2 = ( )/2 = )()( )( 35 )()( )( '   ×        ee e ee e Meanw wX    

Proposed Method 9  Interpolation in Sample pixels S 0 = {18, 40, 67} Cover image X S 90 ={47, 40, 43} Interpolation X ’ Mean 0 =(S 0 (1)+S 0 (3))/2 =(18+67)/2 =42.5 Mean 90 =(S 90 (1)+S 90 (3))/2 =(47+43)/2 =45 u= ( Mean 45 + Mean 135 )/ 2 = ( )/2 =

Proposed Method(Cont.) 10  Embedding(Non-Sample pixels) (1/2) Cover image XInterpolation X ’ RM LM RM+1 LN Difference E RN LM-1 LM RM - =

Proposed Method(Cont.) 11  Embedding(Non-Sample pixels) (2/2) Interpolation X ’ Difference E RM LM RM+1LM-1 Difference E ’ W= = Interpolation X ’ Watermarked image

Proposed Method(Cont.)  Embedding(Sample pixels) Watermarked image Interpolation X ’ 00 Difference E LNRN LMRM LMRM LM-1RM+1 - = 12

Proposed Method(Cont.)  Embedding(Sample pixels) Interpolation X ’ 00 Difference E LMRM LM-1RM+1 W= Difference E ’ Interpolation X ’ Watermarked image + = 13

Proposed Method(Cont.)  Extracting(Sample pixels) Watermarked image Interpolation X ’ Difference E ’ + = LM=-1 RM=0 LN=-2 RN=1 W 2 = Difference E = 14

Proposed Method(Cont.)  Extracting(Non-Sample pixels) Watermarked images Interpolation X ’ = - Difference E ’ = Difference E ’ Cover Image X LM=0 RM=1 LN=-3 RN=4 W 1 = W= W 1 ∥ W 2 15

 To distinguish the Boundary pixel is corresponding to genuine or pseudo Pixel in cover image: Proposed Method 16  Boundary Map (B) x=0 x ’’ =-1x ’’ =1 x=255 x ’’ =254x ’’ =256 X X Underflow Overflow Pixel in cover image: Watermarked pixel: B=…0To add ‘0’ in to the boundary map x ’’ =0x ’’ =255 x=1 x ’’ =0x ’’ =2 x=254 x ’’ =253x ’’ =255 B=…1To add ‘1’ in to the boundary map  Overflow and Underflow

Experiment Results 17 TABLE I COMPARISON RESULTS IN TERMS OF THE CAPACITY (bits) AND THE PSNR VALUE (dB) FOR LENA, BABOON, PLANE, AND SAILBOAT

Experiment Results 18 Fig. 1 Performance evaluation of multilayer embedding over standard in test image Lena

Conclusions 19  The computation cost of the proposed method scheme is small.  The proposed scheme could guarantee high image quality without sacrificing embedding capacity.