Image enhancement is largely a subjective process which means that it is a heuristic procedure designed to manipulate an image in order to achieve the pleasing aspects of a viewer. On the other hand image restoration involves formulating a criterion of goodness that will yield an optimal estimate of the desired result.

In image enhancement the degradation is not usually modeled. Image restoration attempts to reconstruct or recover an image that has been degraded by using the prior knowledge of the degradation. That is restoration techniques try to model the degradation and apply the inverse process in order to recover the original image.