Time-Frequency Analysis and Its Application in Digital Watermarking

A review of time-frequency analysis and some aspects of its applications in digital watermarking are presented. The main advantages and drawbacks of various time-frequency distributions are first discussed. The aim of this theoretical overview is to facilitate an appropriate distribution selection in a specific application. Different aspects of the time-frequency analysis when applied to digital watermarking are then presented. In particular, the method that maps time-frequency characteristics of a host signal to the pseudo noise watermark sequence is thoroughly discussed. This approach is presented in the multidimensional form and then applied to digital audio, digital image, and digital video watermarking. Finally, the theoretical considerations are illustrated by various numerical and real-life examples.