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

This paper proposes a local adaptive thresholding method based on a water #ow model, in which an image surface is considered as a three-dimensional (3-D) terrain. To extract characters from backgrounds, we pour water onto the terrain surface.Water #ows down to the lower regions of the terrain and "lls valleys. Then, the thresholding process is applied to the amount of "lled water for character extraction, in which the proposed thresholding method is applied to gray level document images consisting of characters and backgrounds. The proposed method based on a water #ow model shows the property of locally adaptive thresholding. Computer simulation with synthetic and real document images shows that the proposed method yields e!ective adaptive thresholding results for binarization of document images. 2001 Pattern Recognition Society. Published by Elsevier Science Ltd. All rights reserved.