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 libraryElectronic 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’)