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UC Lab Kyung Hee University, South Korea
January 09 , 2015
UC Lab Kyung Hee University, South Korea 2
UC Lab Kyung Hee University, South Korea 3
โข Millions of images are shared every day through the SNS
โข Many of these images end up in the hands of unknown
people that use them in an illegal and malicious manner
โข Mechanisms for ensuring the ownership and protecting the
copyright are utterly required to settle potential disputes
ImageWatermarking
UC Lab Kyung Hee University, South Korea 4
Convenience
Imperceptibility
Robustness
The information should be extracted from the original image
A watermark has to be imperceptible
A watermark needs to be robust against image modifications
visualization
frequency domain
โข Quality
Optimal color channel selection
โข Accuracy rate in the extraction process
Optimal threshold based on the Otsu method.
UC Lab Kyung Hee University, South Korea 5
UC Lab Kyung Hee University, South Korea 6
Article Key concept Limitations
Xiang-yang [2012] Fourier transform
Least square support vector
machine (LS-SVM)
High computation time for LS-SVM training.
Niu [2011] Nonsubsampled coutourlet
transform (NSCT)
Support vector regression (SVR)
Low performing NSCT and computation time in
extraction process.
Song [2012] Curvelet transform
Coefficient quantization technique
Weakness under lossy JPEG compression
Chou [2010] Wavelet transform
Just noticeable color difference
(JNCD)
Weakness under geometric operations and hue
modification.
UC Lab Kyung Hee University, South Korea 7
Color Images
4-DWTCoeffientBlocking
CoeffientDifference
Optimum Selection
Embedding Rule
Coefficient Unblocking
4-IDWTEmbedded
Image
Binary Watermark
Bit shufflingCombined
Key
Recovered Watermark
Bit Reshuffling
Extraction Rule
Coefficient Difference
Coefficient Blocking
4-DWTModified Image
Adaptive threshold
Otsu method
Channel
Attacks
Embedding process
Extraction process
UC Lab Kyung Hee University, South Korea 8
Color Images
4-DWTCoefficient Blocking
Coefficient Difference
Optimum Selection
Embedding Rule
Coefficient Unblocking
4-IDWTEmbedded
Image
Binary Watermark
Bit shufflingCombined
Key
HL4
(C(HL,i))
LH4
(C(LH,i))
Block 1
C(HL,1 )
Block 2 Block n
C(HL,2) C(LH,1 ) C(LH,2)C(HL,n) C(HL,n)
Coefficient difference
Nu
mb
er o
f blo
cks Before embedding
The embedding process
Coefficient difference
Nu
mb
er o
f blo
cks
After embedding
0-bits
1-bits
y1 y2
โ๐,๐ (= ๐ถ๐ฟ๐ป๐,๐ โ ๐ถ๐ป๐ฟ๐,๐ )
โ๐,๐โ โ๐,๐๐
๐ป๐0 = ๐ฆ1 โ โ๐,๐
๐ ๐ฆ1 =1
๐0 ๐=13 ๐=1
๐0 โ๐,๐๐
๐ถ๐ฟ๐ป๐,๐_๐๐๐ก = ๐ถ๐ฟ๐ป๐,๐_๐๐๐ก + ๐ป๐0 ; โ๐ถ๐ฟ๐ป๐,๐_๐๐๐ก โฅ ๐ถ๐ป๐ฟ๐,๐_๐๐๐ก
๐ถ๐ป๐ฟ๐,๐_๐๐๐ก = ๐ถ๐ป๐ฟ๐,๐_๐๐๐ก + ๐ป๐0 ; โ๐ถ๐ฟ๐ป๐,๐_๐๐๐ก < ๐ถ๐ป๐ฟ๐,๐_๐๐๐ก
UC Lab Kyung Hee University, South Korea 9
LL4 HL4
LH4 HH4
HL4
(C(HL,i))
LH4
(C(LH,i))
Block 1
C(HL,1 )
Block 2 Block n
C(HL,2) C(LH,1 ) C(LH,2)C(HL,n) C(HL,n)
The embedding process
UC Lab Kyung Hee University, South Korea 10
โ1,๐ โ1,๐บ โ1,๐ต
โ2,๐ โ2,๐บ โ2,๐ต
โฎ โฎ โฎ
โ๐โ1,๐ โ๐โ1,๐บ โ๐โ1,๐ต
โ๐,๐ โ๐,๐บ โ๐,๐ต
โ๐,๐ โ ๐ฆ1 ; โ 0 โ bit
โ๐,๐ โ ๐ฆ2 ; โ 1 โ bit
UC Lab Kyung Hee University, South Korea 11
The extraction process
Embedded Image
Recovered Watermark
Bit Reshuffling
Extraction Rule
Coefficient Difference
Coefficient Blocking
4-DWTModified Image
Adaptive threshold
Otsu method
Attacks
HL4
(C(HL,i))
LH4
(C(LH,i))
Block 1
C(HL,1 )
Block 2 Block n
C(HL,2) C(LH,1 ) C(LH,2)C(HL,n) C(HL,n)
Coefficient difference
Nu
mb
er o
f blo
cks
After embedding
Optimal threshold0-bits
1-bits
๐ป๐1 = ๐ฆ2 โ โ๐,๐
๐ ๐ฆ2 =1
๐0 ๐=13 โ๐=๐๐1,๐
๐
โ๐,๐๐ < ๐ฆ2
๐ถ๐ฟ๐ป๐,๐_๐๐๐ก = ๐ถ๐ฟ๐ป๐,๐_๐๐๐ก + ๐ป๐1
๐ถ๐ป๐ฟ๐,๐_๐๐๐ก = ๐ถ๐ป๐ฟ๐,๐_๐๐๐ก โ ๐ป๐0 ๐ถ๐ฟ๐ป๐,๐_๐๐๐ก โฅ ๐ถ๐ป๐ฟ๐,๐_๐๐๐ก
๐ถ๐ฟ๐ป๐,๐_๐๐๐ก = ๐ถ๐ฟ๐ป๐,๐_๐๐๐ก โ ๐ป๐1
๐ถ๐ป๐ฟ๐,๐_๐๐๐ก = ๐ถ๐ป๐ฟ๐,๐_๐๐๐ก + ๐ป๐0 ๐ถ๐ฟ๐ป๐,๐_๐๐๐ก < ๐ถ๐ป๐ฟ๐,๐_๐๐๐ก
โ๐,๐๐ โฅ ๐ฆ2
๐ถ๐ฟ๐ป๐,๐_๐๐๐ก = ๐ถ๐ฟ๐ป๐,๐_๐๐๐ก๐ถ๐ป๐ฟ๐,๐_๐๐๐ก = ๐ถ๐ป๐ฟ๐,๐_๐๐๐ก
UC Lab Kyung Hee University, South Korea 13
(a) (b) (c) (d)
(e) (f) (g) (h)
UC Lab Kyung Hee University, South Korea 14
Table 1: Quality of embedded images
Image CPSNR (dB) SSIM
Airplane 45.81 0.992
Girl 53.13 0.999
House 43.41 0.995
Lena 48.17 0.999
Mandrill 46.75 0.999
Peppers 44.57 0.999
Sailboat 43.73 0.998
Splash 55.28 0.999
Image quality after embedment
Original Watermarked
UC Lab Kyung Hee University, South Korea 15
Watermark robustness after extraction (NC value)
0.4
0.5
0.6
0.7
0.8
0.9
1
Non-attack Scaling Cropping 25% Rotation (0.5) Gaussian noise
Geometric attacking
Airplane Girl House Lena Mandrill Peppers Sailboat Splash
0.4
0.5
0.6
0.7
0.8
0.9
1
Histogram
equalization
Average filter 7x7 Median filter 7x7 Gaussian filter 7x7
Non-geometric attacking
Airplane Girl House Lena Mandrill Peppers Sailboat Splash
0.4
0.5
0.6
0.7
0.8
0.9
1
JPEG QF=10% JPEG QF=20% JPEG QF=40% JPEG QF=60%
Lossy JPEG compression
Airplane Girl House Lena Mandrill Peppers Sailboat Splash
UC Lab Kyung Hee University, South Korea 16
0.4
0.5
0.6
0.7
0.8
0.9
1
Scaling Cropping
20%
Rotation (5) Gaussian
noise
Median
filter 3x3
Gaussian
filter 3x3
JPEG
QF=30%
JPEG
QF=40%
JPEG
QF=70%
Robustness comparison - NC
Niu [7] Proposed
40.71
48.17
36 38 40 42 44 46 48 50
Niu's method
Proposed method
Imperceptibility comparison - CPSNR (dB)
optimal channel selection
โข Combined key
optimal threshold
high quality of watermarked image is obtained
robust against most types of attacks
17
UC Lab Kyung Hee University, South Korea 18
UC Lab Kyung Hee University, South Korea 19