robust and transparent watermarking scheme for colour images
DESCRIPTION
Robust and transparent watermarking scheme for colour images. Speaker : Po-Hung Lai Adviser : Chih-Hung Lin Date : 2009.1.5. Article History and Author. Article History Published in IET Image Processing Received on 6th April 2008 Revised on 2nd February 2009 Author - PowerPoint PPT PresentationTRANSCRIPT
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Robust and transparent watermarking scheme for colour imagesSpeaker : Po-Hung Lai
Adviser : Chih-Hung Lin Date : 2009.1.5
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Article History and Author
Article HistoryPublished in IET Image ProcessingReceived on 6th April 2008Revised on 2nd February 2009
AuthorK.-C. Liu & C.-H. Chou
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Outline
Introduction Estimation of JND profiles of colour
images Watermark embedding and extractio
n Simulation results Conclusions
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Introduction
Business
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Introduction
BusinessWATERMARK
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Introduction
WA ARK
圖的正確性 Y?N?
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Introduction
texture, luminance, corner and edge
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Introduction (visual part)
discrete cosine transform (DCT)by Watson’s perceptual model Li et al.adaptively adjust quantisation step sizessmall number of perceptual works can be fo
und Human Visual System (HVS)
watermark was inserted into the perceptually important sub-image
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Introduction (visual part)
Just noticeable colour difference(JNCD)in the uniform CIELAB colour spaceperceptually lossless colour quantisati
on watermark transparencyJNCD threshold
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Introduction (embed part)
Properties of histogramsLin et al. measured the numerous
global features of all pixels and three-dimensional feature space
Invisible watermarking methodcryptographywatermarking
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Introduction (embed part)
Modify pixelsmodifying the intensities of pixels in the blu
e component of the colour image modifying quantisation indices of colour pixels
Spread spectrum watermarking schemewatermark into a four-fork tree in the wavel
et domain of the Y component
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Introduction (defect & improvement)
Fixed step size to quantiseWorse robustness
Modification of the quantisationhelp to improve the performance of the
watermarking scheme.
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Introduction (in this paper)
perceptual redundancy inherentin each wavelet coefficient of the colo
ur image in a more reliable YCbCr
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Estimation of JND profiles of colour images
Tristimulus values Perceptually indistinguishable.
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Estimation of JND profiles of colour images
Color space ， CIELAB (Commission International L’E’ clairage)RGB ， YUV ， YCbCrto overcome the non-uniform colour m
etric that had been discussed by MacAdam
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Estimation of JND profiles of colour images
JNCD In CIELAB space any two colours difference is greater than 2.3Performance
of robustness
In CIELAB space use JNCD to embed transparent watermark
Perceptuallylossless colour quantisation
Modifying quantisation indices embedded transparent watermark
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Estimation of JND profiles of colour images
adaptive JNCD (AJNCD) due to local variations in luminance magnitude is considered to estimate
the adaptive JNCD (AJNCD) for each colour pixel
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Estimation of JND profiles of colour images
is a weighting function between AJNCD
is the average background luminance
is the maximum of the four weighted average of luminance
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Estimation of JND profiles of colour images
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Estimation of JND profiles of colour images
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Estimation of JND profiles of colour images
Luminance contrast is given by f1 texture masking effect is given by f2
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Estimation of JND profiles of colour images
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Estimation of JND profiles of colour images
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Estimation of JND profiles of colour images
Choose YCbCr colour spaceProvides large perceptual redundancyWithout degrading the visual qualityCan resist JPEG ， JPEG2000 ， H.26x
compression attacks
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Estimation of JND profiles of colour images
is the JND threshold
is the MND threshold is a lifting factor minimally noticeable distortion (MND)
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Estimation of JND profiles of colour images
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Watermark embedding and extraction
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Watermark embedding and extraction
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Watermark embedding and extraction
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Watermark embedding and extraction
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Watermark embedding and extraction
is the energy of the estimated JND profile
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Watermark embedding and extraction
The plots of relative distortion capacity versus band number are obtained
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Watermark embedding and extraction
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Watermark embedding and extraction
To guarantee the transparency and robustness
JND tuned by the associated JND value key information facilitate the portability of key
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Watermark embedding and extraction
full-band JND profiles Bitstream image is too bad JPEG2000 coder reduced to 1 k bytes
Sub-band JND profile tuned colour quantisation JNDs decodedwatermarked coefficients
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Watermark embedding and extraction
= quantisation index = quantisation step size
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Watermark embedding and extraction
= decoded JND threshold
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Watermark embedding and extraction
， B=bit sequence = binary value of 1 or 0 is a random value of 1 or 21 for modu
lating qZ,i to higher or lower index
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Watermark embedding and extraction
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Simulation results
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Simulation results
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Simulation results
To verity the robustness
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Simulation results
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Simulation results
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Simulation results
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Simulation results
Second experiment Huang et al.
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Simulation results Stimark software
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Simulation results
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Simulation results
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Simulation results
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Simulation results
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Simulation results
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Conclusions
By using the perceptual redundancy Watermark transparency is achieved Quite robust in the face of various
attacks.