1

Adaptive Data Hiding in Palette images by Color Ordering and Mapping With Security

ProtectionAuthors: Chih-Hsuan Tzeng, Zhi-Fang Yang, and Wen-Hsiang TsaiSource: IEEE Transactions On Communications, Vol. 52, No. 5, May 2004, pp. 791-800.

Adviser ： Wen-Chung Kuo

Jiin -Chiou Cheng

Repoter ： Wei-De Hsu

2

Outline

• Introduction • The proposed method

– Color-ordering relationship– Color-mapping function– Data-embedding process– Data-extraction process

• Experimental results• Conclusions

3

Introduction

• Gifshuffle– The idea is to permute the colors in the

palette of an image in a specific order in accordance with the secret data. (256!)

indexes colors

0 0 0 0

1 0 255 0

2 255 0 0

3 0 0 255

Ex: 4!

[6] M. Kwan. (1998) GIF Colormap Steganography. [Online]. Available: http://www.darkside.com.au/gifshuffle/

4

Introduction

(a) The original image. (b) Replacement by the closet color.

(c) Replacement by the neighboring color.

Three colors c1, c2, c3, with RGB values (0, 174, 239), (57, 181, 74), and (236, 0, 140) are contained in the sample images.

[12] J. Fridrich and R. Du, “Secure steganographic methods for palette images,” in Proc. 3rd Int. Workshop Information Hiding, Dresden, Germany, 1999, pp. 47–60.

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Color-ordering relationship

c1 c2 c3

c4

6

Proposed data-embedding process

12 12 12

12 12

12 12 16

10 10

12 12 12

12 60

12 16 17

10 18

00

26

148

48

7

Proposed data-embedding process

otherwise ,embeddable-non

and ,embeddable dc TTx

12 12 12

12 12

12 12 12

12 6000

148

10 ,2 dc TT

Non-embeddable

8

Proposed data-embedding process

otherwise ,embeddable-non

and ,embeddable dc TTx

12 12 16

10 10

12 16 17

10 6026

48

10 ,2 dc TT

embeddable

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Color-mapping function

otherwise.

if

if

if

if

0,

1,

0,

1,

0,

),...,,('4

'3

'3

'2

'2

'1

'1

'4

'1

ccc

ccc

ccc

cc

cccfcm

'4

'3

'2

'1 cccc

'3c

'1c

'4c

'2c

c

c1 c2 c3

c4

10

Color-mapping function

12'3 c 17'

1 c

10'4 c

otherwise.

if

if

if

if

0,

1,

0,

1,

0,

),...,,('4

'3

'3

'2

'2

'1

'1

'4

'1

ccc

ccc

ccc

cc

cccfcm

48

36

16'2 c

18c

12'3 c 17'

1 c

10'4 c

16'2 c

16c

Hiding 0 Hiding 1

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Data-extraction process

otherwise.

if

if

if

if

0,

1,

0,

1,

0,

),...,,('4

'3

'3

'2

'2

'1

'1

'4

'1

ccc

ccc

ccc

cc

cccfcm

36

12'3 c 17'

1 c

10'4 c

16'2 c

16c

12

Experimental results

colors). 256( 256256 15640 bits/44.8dB

10 ,2 dc TT

13

Experimental results

colors). 256( 300213 2003 bits/43.7dB

10 ,2 dc TT

14

Experimental results

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Conclusions

• The experimental results show that secret data can be embedded and extracted successfully without producing visual artifacts in the cover image.

• A good balance between stego-image quality and data-embedding capacity can be achieved.