ABSTRACT
This chapter discusses the purposes and properties of digital image watermarking. The word ‘image’ comes from the Latin word imago, which stands for an artifact of depicting the external perception of any object, experienced through the human visual system. In the spatial domain, the image pixels are directly modified by the watermark image pixels to produce the watermarked image. Most signal processing actions are frequently performed and mathematically expressed in an exact field, known as a frequency domain. Frequency domain watermarking techniques generally insert the authentication mark into an image by modifying the higher-frequency components in order to enhance the robustness of the mark. Moreover, hardware implementation for spatial methodologies is less complex and the computational cost is also very low with respect to the frequency domain techniques. The inverse transforms of both the domains were then performed over the watermarked image before transmitting.
