1. A Restricted Region-based Data-hiding Scheme
Chair Professor Chin-Chen Chang
Feng Chia University
National Chung Cheng University
National Tsing Hua University

2. Outline
Introduction
Proposed scheme
Experimental results
Conclusions

3. Introduction (1/3) Traditional information hiding
Secret Message:
(Cover Image)
(Stego Image)

4. Introduction (2/3) (cover pixels) 50 60 61 78 90 93
100 95
203
175 30
150
179
188
156 89
(cover pixels)
(binary representation of cover pixels)
Secret Message:
(binary representation of stego pixels)

5. Introduction (3/3) Our proposed scheme Secret Message: 110110110011
Protected Region
(Cover Image)
(Stego Image)

6. Embedding Select protected regions Generate a location map
Compress the location map with Huffman coding
Embed the information

7. Select Protected Regions50 60 61 78 90 93
100 95
203
175 30
150
179
188
156 89
Protected region

8. Generate a Location Map
1 changeable pixel
0  unchangeable pixel 50 60 61 78 90 93
100 95
203
175 30
150
179
188
156 89 1
Location map

9. Generate Tokens Get the tokens Type 1: 0…01 (ending with 1)
Type 2: (eight 1s)
Type 3: single 1
Type 4: 00…00(ending with 0) 1
Token
Frequency 1 2
000000

10. Condensed location map: 001101
Get the Huffman Code
Get a condensed location map
root 1 2
000000
Token
Frequency
codeword 1 00 2
000000 01
Location map:
Condensed location map:

11. Condensed Huffman code:
Header:
Ex. 1:
Cover pixel:
Condensed Huffman code: 10 1
Stego pixel:
1: embedded
0: unembedded
Header: 10

12. Header:
Ex. 2:
Cover pixel:
Huffman code: 10
Stego pixel:
1: embedded
0: unembedded
Header: 11

13. Payload Header: 11 Huffman code: 001101
Secret information
Header: 11
Huffman code:
Secret information:
Payload: 11• •

14. Huffman code (Condensed location map): 001101
Ex 1:
Huffman code (Condensed location map):
The size of condensed location map = 6 (bits)
= 4
Number of needed changeable pixels
For header
For condensed location map 1 4
Private Key: 11011
(Location map)

15. Huffman code (Condensed location map): 001101
Ex 2:
Huffman code (Condensed location map):
The size of condensed location map = 6 (bits)
= 4
Number of needed changeable pixels
For header
For condensed location map 1
Private Key: 1111
(Location map)

16. (binary representation of cover pixels) 50 60 61 78 90 93
100 95
203
175 30
150
179
188
156 89
(cover pixels)
(binary representation of cover pixels)
Payload: 11• •
Private key: 1111 51 60 63 77 91 93
102 95
203
175 30
150
179
188
156 89
(stego pixels)
(binary representation of stego pixels)

17. Hiding capacity (bits)
Experimental Results
512 X 512 = (bits)
Changeable and
unchangeable
region
Information
Unchangeable region (white)
(512 X 512)
Huffman code (bits)
39972
39822
Two LSBs
Private key (bits)
21601
19911
Hiding capacity (bits)
382306
377944
PSNR (dB)
Three LSBs
13324
13274
593445
582826

18. Conclusions Simple and efficient Hiding capacity is large
Good stego image quality