K.-C. Liu, C.-H. ChouE-mail: kcliu@tht.edu.tw

IET Image Process., 2009, Vol. 3, Iss. 4

Objectiveto 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 ofcolour images

where,JNCD = Just Noticeable Color DifferenceAJNCD = adaptive JNCDE(Y ) = average background luminance∆Y = maximum of the four weighted average

of luminance difference around the color pixel.

Relationship between f1 & E(Y)

Relationship between f2 & ∆Y

Calculating the average background luminanceOriginal Calculated

Weighting the Y component

Embedding sub-bands and theassociated 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

+

=

+

=

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

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