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Robust and transparent watermarking scheme for colour images

Robust and transparent watermarking scheme for colour images. K.-C. Liu, C.-H. Chou E-mail: kcliu@tht.edu.tw IET Image Process., 2009, Vol. 3, Iss. 4. Objective. to design the color watermarking scheme.

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Robust and transparent watermarking scheme for colour images

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  1. Robust and transparent watermarking schemefor colour images K.-C. Liu, C.-H. Chou E-mail: kcliu@tht.edu.tw IET Image Process., 2009, Vol. 3, Iss. 4

  2. 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.

  3. Estimation of JND profiles ofcolour 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.

  4. Relationship between f1 & E(Y)

  5. Relationship between f2 & ∆Y

  6. Calculating the average background luminance • Calculated • Original

  7. Weighting the Y component

  8. Embedding sub-bands and theassociated private key

  9. Minimally Noticeable Distortion(MND) where, • tZ, fb(x, y) = JND threshold of the pixel in color component Z at (x, y), • ε = lifting factor

  10. Quantization index where Then

  11. Relationship between modulation error and adaptive quantization step size

  12. + =

  13. + =

  14. 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

  15. Thank You

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