Selective diffusion involving reaction for binarization of bleed-through document images

Binarization has always been a challenging problem in document image processing because of various types of degradation. In this paper, we present a nonlinear reactiondiffusion model for binarization of bleed-through document images, which is the PeronaMalik equation involving diffusion coefficient based on structure tensor along with a nonlinear reaction term. The Perona-Malik diffusion is utilized to selectively smooth document images with bleed-through removal. Meanwhile, the nonlinear reaction term takes the responsibility for the desired binarization. In order to solve our model numerically, we develop a parallel-series splitting algorithm by combining finite differencing with two kinds of splitting methods in the literature. Our algorithm is tested on seven publicly available datasets (DIBCO 2009 to 2014 and 2016). The experimental results show that our method averagely outperforms six relevant models for the nineteen document images with bleed-through in the DIBCO series datasets. (C) 2020 Elsevier Inc. All rights reserved.