Noise models in digital image processing

Image processing has a great importance in every field (Medical, Education, Astronomy and Defense) now a days. Images get corrupted due to noise present in them. To identify this noise, in this paper, methods and various techniques are described. Noise removal is the important in order to retain the quality of the image. During image acquisition and transmission noise is added to images. Noise cannot be identified through naked eyes. So it is necessary to identify noise using some models. In this paper, types of noise model is discussed.