Removal of interfering strokes in double-sided document images

Abstract

This paper addresses a special problem with historical document images where handwritten characters from the reverse side appear as noise on the front side and even interfere with the front side characters. A novel method to extract clear textual images from interfering and overlapping areas of text is presented here. The proposed algorithm is interesting in that, with an observation that the edges of the seeping strokes from the reverse side are not as sharp as those on the front side, it adopts an edge detection approach to suppress unwanted background patterns. By further concentrating on the orientation of the strokes, other remaining long and strong noisy edges are removed by using an orientation filter and a size filter. The proposed method proves to perform well regardless of the intensity differences between the foreground writing and the interfering strokes. The segmentation results of real images are shown and evaluated.