Considering a fast development and a huge amount of multimedia contents on the Internet, there is a need to improve security of these data.One of the most important security methods is the digital watermarking technology that allows embedding of a watermark in the multimedia files and extraction of it without affecting the perceptual quality of the multimedia files. This paper describes types of watermarking techniques, the way of their implementation as well as their robustness to different type of attacks. In this paper, we present practical examples of the image watermarking in a frequency domain. Our examples are written and illustrated in the software package Matlab.
