ABSTRACT
This chapter introduces the fundamental digital watermarking techniques, including the spatial domain and frequency domain embedding approaches and fragile and robust watermarking techniques. 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. In general, the watermark capacity of substitutive watermarking in the spatial domain is larger than other watermarking approaches. The rounding error problem exists in substitutive watermarking in the frequency domain. In contrast to the substitutive approach, the additive watermarking approach does not consider the specific bits of a pixel. The chapter describes the substitutive and multiplicative watermarking methods in the frequency domain, and introduces a watermarking scheme based on vector quantization (VQ). It also presents a rounding error problem in frequency domain methods. Frequency domain embedding inserts the watermark into a prespecified range of frequencies in the transformed image.
