1. Hiding Data Reversibly in an Image via Increasing Differences between Two Neighboring Pixels
Source: IEICE-Transactions on Info and Systems
,Vol.E90–D, No.12 pp , Dec. 2007
Authors: Ching-Chiuan Lin and Nien-Lin Hsueh

2. Outline
Introduction
Proposed Method
Experimental Results
Conclusions

3. Send Introduction Reversibly Image Steganography Sender Receiver
Secret data: 1001…
Cover image
Secret data: 1001…
Send
Cover image
Stego-image

4. Proposed Method Main Idea Capacity = 2570 bits Pixels histogram
Pixel differences
histogram
Cover image

5. Proposed Method(Cont.)
Pixel differences
User messages:0101 4 5 7 6 8 4 5 7 8 9
Use zigzag order 4 5 6 7 8 1 -2 2 1 2 -3 3 4 5 7 8 9
peak

6. Proposed Method(Cont.)
Embedding rule:
Embed “0”
|xi – xi-1| = 1
Embed “1”
|xi – xi-1| = 2
Problem
Peak = 1
254
255 1
253 90
Problem 1
Solution 1
(254, 255) → (254, 256)
(1, 0) → (1, -1)
Skip 0 and 255
Problem 2
Solution 2
Cover image
(253, 254)→(253, 255)
Recorded!
When change into 0
and change into 255
Semi –saturation pixel
Fresh –saturation pixel
Overhead information

7. Proposed Method(Cont.)
LSB-replacement
Embedding overhead information
Pixel differences
Embedding(Overhead Information)LSBs +
User messages
Cover image (8×8)

8. Overhead Information =3 Cover image (8×8×8)
LDP: a flag denoting whether the difference plane is the last one
NDP: the number of difference planes in the stego-image
NS: the number of semi-saturation pixels
NFS: the number of fresh saturation pixels encountered
IFSs: the indexes of fresh saturation pixels encountered
P: peak
Estimated overhead information size 12 15 16 51 95 71 92 96 34 61 14 85 21 94 41 11 55 64 65 32 43 46 54 74 89 18 69 75 1 82 62 59 98 =3
Cover image (8×8×8)
v = |LDP|+|NDP|+|NS|+|NFS|+|P|+NS×u bits
= ×6
= 43 bits
Log2 8*8 = 6 bit
LDP: 0 or 1 (1 bit)
NDP: 0~255 (8 bits)
Enbedding (OI+MP1)LSB+UMsg By Difference pixels
NFS: 4 bits
P: 8 bit
v’ = |LDP|+|NDP|+|NS|+|NFS|+|P|+|IFSs|
= ×6
= 37 bits
IFSs: 2×6 = 12 bits

9. Overhead Information(Cont.)12 15 16 51 95 71 92 96 34 61 14 85 21 94 41 11 55 64 65 32 43 46 54 74 89 18 69 75 1 82 62 59 98
(OI+MP1)LSBs: ….. (43 bits)
OI: ….. (37 bits) - =
6 bit
(MP1)
Secret message: 00011…… …
Cover image (8×8)
(OI+MP1)LSBS
(UMsg)
(MP1)

10. Embedding Cover image (4×4) User message: 01100 ZigZag Scan order62 61 58 63 59 60 64 57
Cover image (4×4)
User message: 01100
ZigZag Scan order 62 61 58 59 63 60 64 57
Difference values -1 -3 1 3 -2 5 -5 4
New Difference values -1 -4 2 4 -3 6 1 -6 5
Stego-image 62 61 57 58 60 63 64 59 56

11. Extracting P = 1 User message: 01100 Stego-image Recovered image62 61 57 58 60 63 64 59 56
Recovered image 62 61 58 59 63 60 64 57
New differences -1 -4 2 4 -3 6 1 -6 5
Original differences -1 -3 1 3 -2 5 -5 4
User message: 01100

12. Experiment Results

13. Experiment Results(Cont.)

14. Conclusion
A large amount of messages can be embedded in a host image and it can be reconstructed without using any information from the original host image.
A smooth image can offer more payload capacities than a complex one.