Here, Image Processing means Digital Image Processing.
Essential of Digital Image Processing is Analog→(Input)→Digital→(Process)→Digital→(Output)→Analog. Analog is an important signal that supports physical phenomenons on the natural world, or input of information-win for human. Namely first, information which is original analog image is digitized(Sampling, Quantization) as digital image by using scanner or camera. Next, it is processed and extracted as required Analog image or information finally by using computers. It is a purpose of this process.