ABSTRACT
Podilchuk and Delp have presented a general framework for watermark embedding and detection/decoding, comparing the differences of various watermarking algorithms and applications in copyright protection, authentication, tamper detection, and data hiding. This chapter introduces the fundamental digital watermarking techniques, including the spatial-domain and frequency-domain embedding approaches and fragile and robust watermarking techniques. Spatial-domain watermarking is the modifying of pixel values directly on the spatial domain of an image. Substitution watermarking in the spatial domain is the simplest watermarking algorithm. The chapter describes the substitution and multiplicative watermarking methods in the frequency domain, and presents the watermarking scheme based on vector quan-tization. It also presents a rounding error problem in frequency-domain methods. The fragile watermark provides a solution for ensuring if a received image can be trusted. The recipient will evaluate the hidden fragile watermark to see whether the image is altered.
