Digital signal processing (DSP) is the study of signals in a digital representation and the processing methods of these signals. DSP and analog signal processing are subfields of signal processing. DSP includes subfields like: audio signal processing, control engineering, digital image processing and speech processing. RADAR Signal processing and communications signal processing are two other important subfields of DSP.
Since the goal of DSP is usually to measure or filter continuous real-world analog signals, the first step is usually to convert the signal from an analog to a digital form, by using an analog to digital converter. Often, the required output signal is another analog output signal, which requires a digital to analog converter.
The algorithms required for DSP are sometimes performed using specialized computers, which make use of specialized microprocessors called digital signal processors (also abbreviated DSP). These process signals in real time and are generally purpose-designed application-specific integrated circuits (ASICs). When flexibility and rapid development are more important than unit costs at high volume, DSP algorithms may also be implemented using field-programmable gate arrays (FPGAs).
The Scientist & Engineer’s Guide to Digital Signal Processing by Steven W. Smith.
Mixed Signal and DSP Design Techniques edited by Walt Kester.
Numerical Recipes in C : The Art of Scientific Computing by William H. Press , Brian P. Flannery , Saul A. Teukolsky , William T. Vetterling.
Fundamentals of Image Processing by Ian T. Young, Jan J. Gerbrands, Lucas J. van Vliet