Abstract
The research to come out with effective and noise-free images is still fresh despite several years' efforts. Even though, recently, several methods have been proposed, each approach has its own merits and limitations. Moreover, outstanding performances are exhibited for the tailored applications but fail in general and create several flaws and blur images of fine structures. The purpose of this study is to compare achievements thus far in the area of nonnatural documents image denoising approaches. Accordingly, existing techniques are organized into nonhomogeneous categories and detailed comparison is exhibited with examples. Finally, remaining problems and possible future directions in the domain of document images denoising are suggested.