Reversible Data Embedding Using a Difference Expansion

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Reversible Data Embedding Using a Difference Expansion. Date: 2012.05.31. Speaker: Meng -Jing Tsai Author: Jun Tian Source: IEEE Transactions on Circuits and Systems for Video Technology, Vol. 13, No. 8, Aug. 2003, page(s ): 890-896. Outline. Introductions Reversible Hiding

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### Reversible Data Embedding Using a Difference Expansion

Date: 2012.05.31

Speaker: Meng-Jing Tsai

Author: Jun Tian

Source: IEEE Transactions on Circuits and Systems for

Video Technology, Vol. 13, No. 8, Aug. 2003, page(s ): 890-896

Outline
• Introductions
• Reversible Hiding
• Difference Expansion
• The Proposed Method
• Experimental Results
• Conclusions
Reversible Hiding
• It can remove the embedded data to restore the original image.

secret data

embedding

extracting

secret data

restore the original image

Difference Expansion

mean = 203

mean = 203

206

201

198

209

-5

+6

h = 206-201 =5 = (101)2

6

expansion

b=1

h’ =209-198

(101b)2 = (1011)2 = 11

5

=2×h+b

=11

pixel pair (201,206) → (198,209)

Data Embedding Difference Expansion Method

location map L

Case1. expandable : 2×h+b

Case2. changeable : LSB(h)

Case3. non-changeable

1

0

0

h=x-y

(x,y)

bitstreamC

Case1. Expandable

location map L=1

mean = 203

mean = 203

206

201

198

209

-5

+6

h = 206-201 =5 = (101)2

6

expansion

b=1

h’ =209-198

(101b)2 = (1011)2 = 11

5

=2×h+b

=11

≦255

≦255

Case2. Changeable

mean = 223

location map L=0

246

200

mean = 223

mean = 223

h = 246-200 =46 = (101110)2

247

177

200

270

expansion

b=1

-46

+47

47

(101110b)2 = (1011101)2 = 93

46

h’ =247-200

=2× +b

≧ 255

≦255

=47

24

(101110)2 = (101111)2 = 47

b=1

23

h

└ ┘

2

-23

+24

≦255

≦255

Expandable Decoding

location map L=1

mean = 203

198

209

b=1

2

h=5

h’ =209-198

3

=11

=(1011)2

x=206

y=201

=(101b)2

Changeable Decoding

location map L=0

mean = 223

246

200

h’=247-200

= 47

b=1

=(101111)2

6

h=( 101110)2 =46

=(10111b)2

5

h=(101110)2

= 46

x=246

y=200

Multiple-Layer Embedding

Layer1

mean = 203

mean = 203

mean = 203

206

192

198

201

214

209

expansion

b=1

h = 206-201 =5 = (101)2

-5

+6

-11

+11

6

(101b)2 = (1011)2 = 11

5

Layer2

expansion

b=0

h = 209-198 =11 = (1011)2

11

(1011b)2 = (10110)2 = 22

11

Experimental Results

“Lena,” with a 516794 bits (1.97 bpp) payload.

“Lena,” with a 39566 bits (0.15 bpp) payload.

“Lena,” with a 141493 bits (0.54 bpp) payload.

Conclusions
• It’s a simple and efficient reversible data embedding method for digital images.
• It achieves very high payload capacity.
• It keeps the distortion low.

Thank you