1. 影像偽裝術 Dr. Chin-Chen Chang
Department of Information Engineering and Computer Science, Feng Chia University, Taichung, Taiwan

2. Data Hiding Hiding system Stego image Cover image
Secret message

3. Cover Carriers
Image
Video
Sound
Text

4. Palette Image Conversion1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
(100,125,73)
Index table
Original Image
Palette
(16 colors)

5. To find the closest pairs
Palette C0 C1 C2 C3 C4 C5 C6 C7 C8 C9
C10
C11
C12
C13
C14
C15
To find the closest pairs 5

6. d(C0, C8) > TH d(C13, C14) > TH Unused C0, C8, C13, C14 C1 C11

7. Encode
Index Table
Original Image
Index Table
Unused
C0,
C8,
C13,
C14

8. A secret message: 1 1 1 1 1 1 1 1
Index Table
Secret bits
C1, C2,
C4, C5
C6, C7
C11, C3
C15, C10
C12, C9 1

9. A secret message: 1 1 1 1 1 1 1 1
Index Table
Secret bits
C1, C2,
C4, C5
C6, C7
C11, C3
C15, C10
C12, C9 1

10. A secret message: 1 1 1 1 1 1 1 1
Index Table
Secret bits

11. Adaptive Embedding MethodC0 C1 C5 C3 C7 C6
C10
C14
C13 S1
C15 S0 S3 C4 C9 C2 C8
C11
C12 S2 S4

12. 4 7 8 2 15 3 1 Secret message: (1 0 1 0 1 0 0 1 0)2 = (338)10 S2 S0 S415 3 1 S2 S0 S4 S3 S1
Index Table

13. C2 C4 C9 C0 C1 C6 C7
C14 C3 C5
C10
C13
C15 C0 C1 C6 C7
C14 C2 C4 C9 C8
C11
C12 C0 C1 C6 C7
C14 C2 C4 C9 S3 S2 S1 S2 S4 S2 S0 S0 S0
S2 X S0 X S1 X S3 X S0 X S2 X S4 X S0 X S2
={(C2,C0,C3,C13,C0,C2,C8,C0,C2),
(C2,C0,C3,C13,C0,C2,C8,C0,C4),
(C2,C0,C3,C13,C0,C2,C8,C0,C9), …,
(C9,C14,C10,C15,C14,C9,C12,C14,C9)}

14. 0: (2,0,3,13,0,2,8,0,2)
1: (2,0,3,13,0,2,8,0,4)
2: (2,0,3,13,0,2,8,0,9)
338: (2,0,3,13,6,4,11,6,2)
32399: (9,14,10,15,14,9,12,14,9)

15. Tzeng et al.’s Data Hiding
Index
Color
(133, 140, 128) 1
(123, 155, 130) 2
(130, 144, 138) 3
(126, 146, 134) 4
(139, 139, 143) 5
(131, 161, 124) 6
(137, 140, 144) 7
(137, 137, 140) C0 C1 C2 C3 C4 C5 C6 C7
Q: Ci > Cj A: ?
The luminance function:
l = 0.3*r *g *b
The color-ordering relationship
Palette

16. > ? < > ? Ex1: Q: A: Ex2: Q: A: c1 c2
(96,139,208)
(119,159,227) c1 c2
l1 = 0.3* * *208 =133.7
l2 = 0.3* * *227 =154.5
< Q: A:
> ?
(245,130,44)
(246,111,143) c1 c2
l1 = 0.3* * *143 =155
l2 = 0.3* * *44 =155
Ex2: Q: A:

17. Q: d(Ci , Cj)=? A: Ex1: C0 C1 C2 C3 C4 C5 C6 C7 Palette
Index
Color l
(133, 140, 128)
136.6 1
(123, 155, 130)
142.7 2
(130, 144, 138)
139.1 3
(126, 146, 134)
138.7 4
(139, 139, 143)
139.4 5
(131, 161, 124)
147.9 6
(137, 140, 144)
139.5 7
(137, 137, 140)
137.3 C0 C1 C2 C3 C4 C5 C6 C7
Palette
Q: d(Ci , Cj)=? A:
Ex1:

18. Q: How to hide a secret bit
A: Using color-mapping function
Ex1: 7 4 6 5 2 3 1 in
Image data 1 1
c’4
c’3
c’2
c’1
137.3
139.4
139.5
147.9

19. Ex2:
139.1
138.7
139.5 1

20. Embedding Process Image data X, palette P, and secret data A
Check the data embeddability of each pixel
Sort the colors of four precedent neighbors and perform the color- mapping function
Is the mapped result equals the secret bit? No
Yes
Embed the secret bit by using the closest color of image data
Embed the secret bit without modifying image data

21. Embedding Process If the secret data is 0 Palette Image data 7 4 6 5 2
Index
Color l
(133, 140, 128)
136.6 1
(123, 155, 130)
142.7 2
(130, 144, 138)
139.1 3
(126, 146, 134)
138.7 4
(139, 139, 143)
139.4 5
(131, 161, 124)
147.9 6
(137, 140, 144)
139.5 7
(137, 137, 140)
137.3 7 4 6 5 2 3 1
Image data
Palette

22. Embedding Process If the secret data is 1 Palette Image data
Index
Color l
(133, 140, 128)
136.6 1
(123, 155, 130)
142.7 2
(130, 144, 138)
139.1 3
(126, 146, 134)
138.7 4
(139, 139, 143)
139.4 5
(131, 161, 124)
147.9 6
(137, 140, 144)
139.5 7
(137, 137, 140)
137.3 7 4 6 5 2 3 1
Image data
Palette 7 4 6 5 2 3 1
Embedded result

23. The Proposed Scheme The clustering c4 c6 c7 c5 c0 c2 c3 c1 S1 S2 S4 S3
Cluster S
Index
Color
Center z S0 4
(139, 139, 143)
(138, 139, 142) 6
(137, 140, 144) 7
(137, 137, 140) S1 5
(131, 161, 124) S2
(133, 140, 128) S3 2
(130, 144, 138)
(128, 145, 136) 3
(126, 146, 134) S4 1
(123, 155, 130)

24. c4 c6 c7 c5 c0 c2 c3 c1 S1 S2 S4 S3 S0 Cluster S Index Color Center z
Luminance l S0 4
(139, 139, 143)
(138, 139, 142)
139 6
(137, 140, 144) 7
(137, 137, 140) S1 5
(131, 161, 124)
147.9 S2
(133, 140, 128)
136.6 S3 2
(130, 144, 138)
(148, 145, 136)
144.9 3
(126, 146, 134) S4 1
(123, 155, 130)
142.7

25. 7 4 6 5 2 3 1 c4 c6 c7 c5 c0 c2 c3 c1 S1 S2 S4 S3 S0 S c z l S0 4
(138, 139, 142)
139 6 7 S1 5
(131, 161, 124)
147.9 S2
(133, 140, 128)
136.6 S3 2
(148, 145, 136)
144.9 3 S4 1
(123, 155, 130)
142.7

26. Combination technique
Secret data: (1011)2=(11)10 c6 S1 S2 c3 S4
Q=3x3x3=27 c7 S3 S0 7 4 6 5 2 3 1 c4 c4 c4 c4 c4 c4 c4 c4 c4 c6 c6 c6 c6 c6 c6 c6 c6 c6 c7 c7 c7 c7 c7 c7 c7 c7 c7
0001
0010
0000 6 4 7 5 2 3 1 c4 c4 c4
11th combination c6 c6 c6 c7 c7 c7

27. c4 c5 c0 c2 c1 c6 S1 S2 c3 S4 c7 S3
Secret data: S0
Q=3x3x3x3x3x3x3x3x3x3x3x2x2=708588 7 4 6 5 1 2 3
Secret data: ( )2(473060)10 C7 C6 C4 C3 C2
473060th combination 7 4 5 1 6 2 3

28. Experimental Results
Host Images
Stego Images

29. Table 1. Embedding performance
41.26
40265
41.12
21405
(f) Garfield-b
40.24
12104
40.65
8168
(e) Garfield-a
42.24
17472
42.22
10349
(c) CCU-Upbar
42.84
5631
42.90
4333
(b) CCU-Logo
40.07
7342
40.04
6160
(d) Palette
41.67
PSNR
40.75
38102
Capacity
Our proposed method
20012
(a) Midnight
Tzeng et al’s method
Schemes
Images

30. Table 2. Embedding capacity and image quality
35.13
145543 70
35.06
60805 62
36.44
17442 23
37.08
61980 9
35.48
59687 16
36.35
179014 36
39.94
63576
188
39.82
20022
200
39.33
10112 29
39.84
46991 22
38.20
33133 40
38.33
112173
115
36.24
124237
110
35.67
57091
107
36.50
17299 24
37.40
70350 11
36.90
44445
37.15
133010 60
35.83
139762 79
35.73
54939 71
36.81
74971
58737 17
36.51
170356
41.26
40265
255
19158
40.40
5893 31
41.48
36568
41.90
7126
41.67
38102
215
39.25
73269
152
39.36
22766
160
39.41
12814 27
37.68
68556 18
37.94
35426 30
38.26
110847 92
40.04
59336
253
39.83
19196
254
40.07
7342
40.82
42630
40.23
22003 49
39.77
73681
155
36.10
128344 91
35.69
56021 88
36.70
77798
35.74
58077 21
36.43
179387 45
36.76
112435
127
36.53
46450
125
38.76
11431 26
37.49
69792 14
36.98
43391 28
37.19
136081 72
PSNR
Capacity
Clusters
(f)
Garfield-b
(e)
Garfield-a
(d)
Palette
(c)
CCU-Upbar
(b)
CCU-Logo
(a)
Midnight

32. Conclusions An adaptive data hiding scheme for the palette images.
High embedding capacity and good image quality

33. Thank you very much for your attention !!