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Digital watermark in digital images and e-books. Why digital watermarking? What is digital watermark? Perceptible and unperceptible watermarks. Embedding and detection Watermark properties: - Detectability Fidelity Optimal embedding strength. Digital watermark for grayscale images
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Digital watermark in digital images and e-books
Why digital watermarking? What is digital watermark? Perceptible and unperceptible watermarks
Embedding and detection • Watermark properties: • - Detectability • Fidelity • Optimal embedding strength
Digital watermark for grayscale images spread spectrum technique AWGN (additive white Gaussian noise) watermark. Optimal embedding strength - normal distribution properties. Optimal embedding strength for lossy compressed image Digital watermark and color image Each color image is three grayscale images combination
Watermark for e-books • Our Virtual library • Electronic book (e-book) • e-book format (PDF, DjVu) • PDF books - classes: • E-books produced by scanning; • E-books originated from DOC or TeX files; PDF file pages need at first to be converted to bitmaps; watermarking is possible, but not robust enough.
Unwatermarked PDF page Watermarked PDF page (‘Faculty of Mathematics Belgrade’)