2.4. IMAGE PROCESSING SYSTEMS
2.4.1. Overview of an Image Processing System
A typical image processing system that involves digital signal processing is shown in Figure 2.25. The input image source I(x,y) is generally an object or a natural scene, hut it may he an image produced by another system. such as a filter, a cathode ray tube (CRT) display monitor, or a video cassette recorder (VCR). The digitizer converts the input source to an electrical signal whose amplitude represents the image intensity and digitizes the electrical signal using an analog-to-digital (AID) converter.
The sequence f(n1,n2) that results from the digitizer is then processed by a digital image processing algorithm. The algorithm may be implemented on a general purpose computer, a microprocessor, or a special purpose hardware. The specific algorithm used depends on the objective, which may involve image enhancement, restoration, coding, understanding. or any combination of them. The result of processing is then displayed, generally for human viewing, but sometimes as an input to another system. The display typically used is a CRT monitor, but may be a photograph or VCR tape, if the result is some symbolic representation. as in image understanding, the display used can also be just a printer.