Transcript Slide 1

K.-C. Liu, C.-H. Chou
E-mail: [email protected]
IET Image Process., 2009, Vol. 3, Iss. 4
Objective
 to design the color watermarking scheme.
 to embed and detect the watermark in the perceptually
significant sub-bands of luminance and chrominance
components of color images in the wavelet domain.
Estimation of JND profiles of
colour images
where,
 JNCD = Just Noticeable Color Difference
 AJNCD = adaptive JNCD
 E(Y ) = average background luminance
 ∆Y = maximum of the four weighted average of
luminance difference around the color pixel.
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Relationship between f1 & E(Y)
Relationship between f2 & ∆Y
Calculating the average
background luminance
 Original
 Calculated
Weighting the Y component
Embedding sub-bands and the
associated private key
Minimally Noticeable Distortion
(MND)
where,
 tZ, fb(x, y) = JND threshold of the pixel in color
component Z at (x, y),
 ε = lifting factor
Quantization index
where
Then
Relationship between modulation
error and adaptive quantization
step size
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a, i and q: attacked by median filtering (7 x 7)
b, j and r: attacked by low-pass filtering (3 x 3)
c, k and s: scaled up by a factor of 2 in each direction
d, l and t: scaled down by a factor of 2 in each direction
e, m and: u attacked by 25% cropping
f, n and v: attacked by removing 52 rows and 52 columns
g, o and w: attacked by self-similarity transform
h, p and x: attacked by noise (variance = 64.0) adding
Thank You