Reversible Data Embedding Using a Difference Expansion

Speaker: Meng-Jing TsaiAuthor: Jun TianSource: IEEE Transactions on Circuits and Systems for Video Technology, Vol. 13, No. 8, Aug. 2003, page(s ): 890-896

Date: 2012.05.31

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Outline

• Introductions– Reversible Hiding– Difference Expansion

• The Proposed Method• Experimental Results• Conclusions

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Reversible Hiding

• It can remove the embedded data to restore the original image.

embedding extracting

secret data

restore the original image

secret data

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Difference Expansion

201 206mean = 203

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

(101b)2 = (1011)2 = 1165

198 209mean = 203

-5 +6

expansionb=1

h’ =209-198=2×h+b=11

21hmean

2hmean

pixel pair (201,206) → (198,209)

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Data Embedding Difference Expansion Method

(x,y)h=x-y

Case1. expandable : 2×h+bCase2. changeable : LSB(h)Case3. non-changeable

bitstream C

location map L

100

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Case1. Expandable

201 206mean = 203

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

(101b)2 = (1011)2 = 1165

198 209mean = 203

-5 +6

expansionb=1

≦255 ≦255

location map L=1

h’ =209-198=2×h+b=11

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≦255 ≧ 255

Case2. Changeable200 246

mean = 223

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

(101110b)2 = (1011101)2 = 934746

177 270mean = 223

-46 +47

expansionb=1

b=1 (101110)2 = (101111)2 = 472423

200 247mean = 223

-23 +24≦255 ≦255

location map L=0

=2× +bh’ =247-200

=47

h－└ ┘2

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Expandable Decodinglocation map L=1

198 209mean = 203

h’ =209-198=11=(1011)2

=(101b)2

b=1h=5

x=206y=201

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Changeable Decoding

200 246mean = 223

h’=247-200= 47=(101111)2

=(10111b)2

h=(101110)2

= 46

b=1h=( 101110)2 =46

x=246y=200

location map L=0

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Multiple-Layer Embedding

201 206mean = 203

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

(101b)2 = (1011)2 = 1165

198 209mean = 203

-5 +6

expansionb=1

Layer1

Layer2 h = 209-198 =11 = (1011)2

(1011b)2 = (10110)2 = 221111

192 214mean = 203

-11 +11

expansionb=0

“Lena,” with a 39566 bits (0.15 bpp) payload. “Lena,” with a 516794 bits (1.97 bpp) payload.

Experimental Results

“Lena,” with a 141493 bits (0.54 bpp) payload.11

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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.

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Thank you for your listening.