1. A novel two-in-one image secret sharing scheme based on perfect black visual cryptography
Source：Journal of Real-Time Image Processing, vol.14, pp.41-50, 2016
Authors：Peng Li, Ching-Nung Yang, Qian Kong
Speaker ：Xiao-Shuang Li
Date ： /06/21

2. Outline Introduction Related Work Proposed Scheme Experimental Results
Conclusions

3. Introduction Two-in-one ISS (TiOISS) Original image Shadow 1 Shadow 2
Previewed image
Reconstructed image

4. Related Work (1/4) Perfect black VCS (PBVCS)
The ‘OR’-ed vector of any k rows of consists of all ‘1’
Example: (2,3)- PBVCS
Basis matrices:

5. Related Work (2/4) Sharing Secret image Shadow 1 Shadow 2 Shadow 3
Stacking

6. Related Work (3/4) Pixel processing with Boolean operations
1. Encoding process with m=3
A: Un-processed m gray secret pixels as a block
: Randomly generated block
: Security mask

7. Related Work (4/4)
2. Decoding process with m=3

8. Proposed Scheme(1/5) Construct gray share matrix Example: (2,3)- PBVCS
Gray basis matrices
: Randomly generated
: the grayscale values are come from

9. Proposed Scheme(2/5)
A diagram of embedding in black share matrix

10. Proposed Scheme(3/5)
The flowchart of the proposed TiOISS scheme

11. Proposed Scheme(4/5) Security and contrast conditions
1. Security condition
2. Contrast condition

12. Proposed Scheme(5/5) The construction methods of PBVCS
(2,n)-VCS by Naor and Shamir’s scheme
(2,n)-PBVCS scheme from (2,n)-VCS

13. Experimental results(1/3)
Secret image
256*256 pixels
Encoded image S’
256*512 pixels
Shadow 1 350*750
Shadow 2 350*750
Shadow 3 350*750
Previewed secret image

14. Experimental results(2/3) The example using qGVCS
Revealed image q=7
390*750 pixels
a=0.19
Revealed image q=6
455*750 pixels
a=0.26
Revealed image q=5
545*750 pixels
a=0.29

15. Experimental results(3/3)

16. Conclusions Reveal a vague secret image by stacking
Decoding the grayscale secret image by fewer XOR
Embed more information in PBVCS to construct a TiOISS scheme
Faster in Decoding than traditional TiOISS

17. Thank you!