1. Halftone Image Data Hiding with Intensity Selection and Connection Selection
Source: Signal Processing: Image Communication 16 (2001) pp
Authors: Ming Sun Fu and Oscar C. Au
Speaker: Hsien-Chu Wu
Date: Nov. 8, 2001

2. Outline
Introduction
Previous works -Data hiding self toggling (DHST) -Data hiding pair toggling (DHPT) -Data hiding smart pair toggling (DHSPT)
The proposed intensity selection algorithm (IS)
The proposed connection selection algorithm (CS)
Experimental results
Conclusions

3. Introduction Halftone image (binary image) -a bit/pixel
-pixel value: 0,1
Gray-level image
-a byte/pixel
-pixel value: 0-255
X  white (0) X< Black (1)

4. Introduction---hiding data in a halftone image1
Host image
Changed image 1 1  

5. Data hiding self toggling (DHST)
Host image
“salt-and-pepper”
artifacts
PRNG(SK) …
Hidden data: …

6. Data hiding pair toggling (DHPT)
Master pixel
> 0 1
PRNG(SK)
Choose one to be the slave pixel
> 1

7. Data hiding smart pair toggling (DHSPT)
Master pixel
> 0 1
PRNG(SK)
Choose one to be the slave pixel by using “connection”
> 1

8. Data hiding smart pair toggling (DHSPT)
The weight of the candidate x x1 x2 x3 x4 x5 x6 x7 x8 x9 1 2

9. Data hiding smart pair toggling (DHSPT)
Connection value
= =6 1
Connection value =0
Connection value
=2+2=4 1

10. The proposed intensity selection (DHSPT-IS)
Hide one bit of the embedded data at M pseudo-random locations
M-pixel-sum parity:
If the hidden bit is not equal to the M-pixel-sum parity, one of the M pixels will be changed.

11. The proposed connectivity selection (DHSPT-CS)
Compute the connection value for each of the M locations and choose the location with the largest connection.

12. Experimental results
Visual quality measure scores:

13. Experimental results

14. Experimental results
Fig 4. Error image for DHSPT

15. Experimental results
Fig. 9. Error image for DHSPT-IS4

16. Experimental results
Fig. 9. Error image for DHSPT-CS4

17. Conclusions The visual quality of IS and CS is better for larger M.
The proposed IS and CS provide a tradeoff between visual quality and computational complexity.