1. Halftone Visual Cryptography
IEEE TRANSACTIONS ON IMAGE PROCESSING, VOL. 15, NO. 8, AUGUST 2006, pp
Zhi Zhou, Gonzalo R. Arce, and Giovanni Di Crescenzo
Reporter: Jen-Bang Feng

2. Visual Cryptography + = + =

3. Visual Cryptography

4. The Proposed Scheme

5. Comparisons
EX.
Block size: 4*4
m = 2
PSNR = 9.03

6. Results
(2, 3)-threshold
(b) (e) extended VC
(c) (d) (f) proposed

7. Results

8. watermark Stacking EDF2 EDF1 EDF1 Lena (gray level) Error diffusion
Data Hiding in Halftone Images With Noise-Balanced Error Diffusion
Soo-Chang Pei, and Jing-Ming Guo
IEEE Signal Processing Letters, Vol.10, No.12, December 2003
Steganography in halftone images:conjugate error diffusion
Ming Sun Fu, Oscar C. Au
Signal Processing 83 (2003) 2171 – 2178

9. + Watermark Stacking * Original Lena
Hybrid Pixel-Based Data Hiding and Block-Based Watermarking for Error-Diffused Halftone Images Soo-Chang Pei (貝蘇章) and Jing-Ming Guo IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY, VOL. 13, NO. 8, AUGUST 2003, Pages:
EDF 1
Watermark +
Stacking
EDF 2 *
NBEDF
Original Lena

10. Conclusions and Comments
Applying VC to halftone images
Classify:
During process
Outside process