... signals were con- verted to sampled data signals by these filters and the signal processing was treated as analog signal processing. But later, the signals were transitioned as discrete-time signals, ... DISCRETE-TIME SIGNALS 7 filters. However, we use the terms digital filter and discrete-time system inter- changeably in this book. Continuous-time signals and systems are also called analog signals and ... image restoration, image under- standing, computer vision, radar and sonar processing, geophysical and seismic data processing, remote sensing, and weather monitoring are some of the applica- tions...