Data Hiding Using Binocular Fusion of Stereo Pairs N. Y. Bai 白 乃 元 Department of Applied Mathematics National Sun Yat-Sen University Kaohsiung, Taiwan 80424

Outlines l Data hiding l Stereograms l Data Hiding Using Binocular Fusion l Experimental Results l Conclusions

Introduction Host image Counterfeit image Hiding image l Data hiding: Embed data into digital media

l Advantages: 1.Protect contents from illegal copy 2.Unauthorized distribution 3.Tampering

l Traditional techniques: 1.Replacing the least-significant bit (Adelson 90) 2.Substituting high-spatial frequency (Bender 96) 3.Using word shifting, line shifting (Bender 96)

Stereograms Perspective projectionStereograms

△ BAC △ EDC

Calculating the (depth) coordinate, we must know : difference between the corresponding image coordinates baseline length focal length

Data Hiding Using Binocular Fusion by Stereo Pairs l Motivation: By the resemblance of the left and right stereo images encountered in the stereographic projection setup l Linear transformation  real time implementation l Lossless algorithm l Adjustable data hiding capacity and PSNR

Original imageMove right one pixel

Encoding The store value and hide to image

Decoding The data hidden can be retrieved losslessly if above equation is satisfied

l Unique subsequence:Continuous pixel values is unique among all possible subsequences formed l Store the value of focal length to lower bits of pixels of the unique subsequence

Experimental Results Images:  Original host images, Lena and F16  Embedding images, baboo and pepper

Lena: 128 x 128 x 8 bits baboo: 80 x 80 x 8 bits pepper: 80 x 80 x 8 bits

F16 : 128 x 128 x 8 bits

Data hiding capacity, PSNR between the host and counterfeit images

Conclusions l Require only linear stereographic transformation  real-time data hiding and extraction feasible l Data hiding capacity and the PSNR between the stereo pairs can be adjusted to meet the demands of specific application needs