A Review on Enhancement of Historical Documents by Image Processing Techniques

Abstract

Historical documents contain important historical information about a person, place, or event and can thus serve as primary sources as important ingredients of the historical methodology. It is very important to preserve the historical documents because it contains information about the civilized past.  It is quite common for such documents to suffer from degradation problems such as presence of smear, strains, background of big variations and uneven illumination, seepage of ink etc. It is necessary to keep these documents alive to preserve important historical information. The transformation of such documents into digital form is essential for maintaining the quality of the original documents. Appropriate filtering methods should be developed in order to remove noise from historical document images and to improve their quality. Image processing techniques such as noise filtering, Histogram equalization and Power law transformation can be used to enhance the quality of historical documents images. In this paper, different methods to improve the quality of historical documents images are considered.

Keywords: Noise filtering, histogram equalization, power law transformation