Date: 2011/05/26 Reporter: Shu-Ping, Yu Advisor: Chun-Ying, Huang
Colored Watermarking Technology Based on Visual Cryptography Author: Hsien-Chu Wu, Chwei-Shyong...
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Transcript of Colored Watermarking Technology Based on Visual Cryptography Author: Hsien-Chu Wu, Chwei-Shyong...
Colored Watermarking Technology Based on Visual Cryptography
Author: Hsien-Chu Wu , Chwei-Shyong Tsai , Shu-Chuan Huang Speaker: Shu-Chuan Huang Date: May 4 , 2005
Outline
• Introduction
• The proposed method
• Experimental results
• Conclusions
Introduction
• Watermarking Technology
• Colored Visual Cryptography
Watermarking Technology
primitive image
watermarkstego-image
Good digital watermarking :
1. Perceptual invisible
2. Security
3. Blindness
4. Multiple watermarks
5. Robustness
Colored Visual Cryptography
Colored Visual Cryptography (cont.)
Colored Visual Cryptography (cont.)
The proposed method
The primitive gray-level image “Lena” Colored watermark
The proposed method (cont.)
Random
The proposed method (cont.)
Range of mean value
Mask
[0, 63]
[64, 127]
[128, 191]
[192, 255]
Mean:186
The color Masks of four kinds of mean values
coding table
The proposed method (cont.)
Experimental Results
Share image 1 Share image 2
Experimental Results
The recovered image from two share images
Experimental Results (cont.)
( a ) The cropping attacked “Lena” ( b ) The recovered image from two share images of cropped “Lena”
Experimental Results (cont.)
( a ) The blurring attacked “Lena” ( b ) The recovered image from two share images of blurred “Lena”
Experimental Results (cont.)
( b ) The recovered image from two share images of sharpened “Lena”
( a ) The sharpening attacked “Lena”
Conclusions
• Provide high robustness by using Visual
Cryptography technique in Digital Watermarking.
• Keep the quality of primitive image.
Watermarking Technology
Based on BTC MethodAuthor: Hsien-Chu Wu, Chwei-Shyong Tsai, I-Su LeeSpeaker: I-Su LeeDate: May 4, 2005
Outline
Introduction
The Proposed method
Experimental results
Conclusions
Block Truncation Coding, BTC
221 212 189 177
213 194 182 184
192 179 187 199
179 186 200 169
512×512
Mean = (221+212+189+…+200+169)/16 = 191M1 = (221+212+213+194+192+199+200)/7 = 204M0 = (189+177+182+184+179+187+179+186+169)/9 = 181
<191 0
>191 1
1 1 0 0
1 1 0 0
1 0 0 1
0 0 1 0
bitmap
BTC decompression
204 204 181 181
204 204 181 181
204 181 181 204
181 181 204 181
bitmap
<191 0
>191 1
0 181
1 204
1 1 0 0
1 1 0 0
1 0 0 1
0 0 1 0
Mean = (221+212+189+…+200+169)/16 = 191M1 = (221+212+213+194+192+199+200)/7 = 204M0 = (189+177+182+184+179+187+179+186+169)/9 = 181
The Proposed method
8-bit grayscale image
binary watermark
Codebook design
min distance
128×128cover-image
codebook
Codebook design (cont.)
codebook
codebook0
codebook1
0
1
Watermark Embedding
codebook0
codebook1
cover-image
binary watermark
0
1stego-image
cover-image
binary watermark
Watermark Extraction (cont.)
stego-image
codebook0
codebook1
0
1
binary watermark
Experimental results
(a) Lena (b) Girl (c) F16
(d) Pepper (e) Splash (f) Tiffany
Experimental results (cont.)
Cover-image stego-image (unit:dB)BTC compression i
mage (unit:dB)
Lena 33.41009155 33.69390363
Girl 37.79463397 37.91506876
F16 30.92604062 31.29763583
Peppers 33.07814946 33.49940908
Splash 36.76107951 37.12370245
Tiffany 33.01723640 33.67697558
Comparison results (PSNR)
Experimental results (cont.)
(a) cropping attack
watermark
bit correct rate
= 0.89063
watermark
bit correct rate
= 0.88672
(b) cropping attack
Experimental results (cont.)
bit correct rate
= 0.88964
bit correct rate
= 0.86230
watermark
watermark
(c) cropping attack
(d) cropping attack
Experimental results (cont.)
bit correct rate
= 0.92969
bit correct rate
= 0.86035
watermark
watermark
(e) sharpening attack
(f) blurring attack
Experimental results (cont.)
Cover image
Lena 0.89063 0.88672 0.88964 0.86230 0.92969 0.86035
Girl 0.88965 0.87891 0.89063 0.86133 0.91406 0.81641
F16 0.88574 0.88769 0.88672 0.86035 0.92188 0.84375
Peppers 0.88574 0.88672 0.88965 0.86230 0.92578 0.73730
Splash 0.88574 0.88672 0.88671 0.86328 0.91992 0.81152
Tiffany 0.85253 0.85351 0.85352 0.84766 0.93554 0.87890
Average 0.88167 0.88005 0.88281 0.85954 0.92448 0.82471
Correct rate of six kinds of attacked watermark
(a) cropping
attack
(b) cropping
attack
(c) cropping
attack
(d) cropping
attack
(f) sharpening
attack
(g) blurring
attack
Conclusions
The proposed method can embed watermark in compressed images directly.
It is simple and efficient to embed watermark in images with using BTC.
Stego-image has good image quality.