Overview

In this chapter, we introduce the basics for watermarking in the spatial domain. Watermarking in the spatial domain, also called additive watermarking, is one of the fundamental schemes in the beginning of digital watermarking researches since 1993. Although this kind of watermarking schemes are simple and easy for implementation, they tend not to be robust congenitally. Employing the error control codes may increase the robustness of spatial domain watermarking. We point out this topic, and hope this can serve as a starting point for inspiring the readers to explore more in the field of digital watermarking.

1 Introduction

The most straightforward and fundamental schemes for the fields of digital watermarking are watermarking in the spatial domain. From the historical perspective, watermarking in the spatial domain started long ago until today, for instance, there are watermarks in the paper bills that we use everyday. At the beginning of the digital watermarking research, while designing the embedding and extraction algorithms, researchers tended to propose schemes to add a pseudo-random noise pattern, or the watermark, to the original image by modifying the luminance values of the pixels in the spatial domain, like the methods in one of the earliest papers with this approach (Tirkel et al. 1993, van Schyndel et al. 1994). We demonstrated one example for such an application in Section 5.2 of Chapter 1 (Wong 1998).

Spatial watermarks are embedded easily and fast, but they are generally considered fragile (Langelaar et...