Image restoration removes or minimizes some known degradations in an image.
It can be seen as a special kind of image enhancement . The most common degradations have their origin in imperfections of the sensors, or in transmission. It is assumed that a mathematical model of the degradation process is known, or that it can be derived by an analysis of other input images. In the following figure we want to illustrate the deblurring of some text in the absence of noise n , by inverse filtering in the frequency domain. The main problem with inverse filters is the amplification of noise.