Document image binarization based on topographic analysis using a water flow model

This paper proposes a local adaptive thresholding method based on a water f low model, in which an image surface is considered as a three-dimensional ( 3-D) terrain. To extract characters from backgrounds, we pour water onto th e terrain surface. Water flows down to the lower regions of the terrain and fills valleys. Then, the thresholding process is applied to the amount of filled water for character extraction, in which the proposed thresholding m ethod is applied to gray level document images consisting of characters and backgrounds. The proposed method based on a water flow model shows the pro perty of locally adaptive thresholding. Computer simulation with synthetic and real document images shows that the proposed method yields effective ad aptive thresholding results for binarization of document images. (C) 2001 P attern Recognition Society. Published by Elsevier Science Ltd. All rights r eserved.