This paper presents a novel iterative deep learning framework and apply it
for document enhancement and binarization. Unlike the traditional methods which
predict the binary label of each pixel on the input image, we train the neural
network to learn the degradations in document images and produce the uniform
images of the degraded input images, which allows the network to refine the
output iteratively. Two different iterative methods have been studied in this
paper: recurrent refinement (RR) which uses the same trained neural network in
each iteration for document enhancement and stacked refinement (SR) which uses
a stack of different neural networks for iterative output refinement. Given the
learned uniform and enhanced image, the binarization map can be easy to obtain
by a global or local threshold. The experimental results on several public
benchmark data sets show that our proposed methods provide a new clean version
of the degraded image which is suitable for visualization and promising results
of binarization using the global Otsu's threshold based on the enhanced images
learned iteratively by the neural network.

本文提出了一种新的迭代深度学习框架，并将其应用于文档增强和二值化。通过学习文档图像中的退化过程，该网络能够逐步细化输出，实现文档增强。通过在全局或本地阈值下使用增强的图像，可以获得二值化图。实验结果表明，所提出的方法适用于可视化和基于 Otsu 阈值的二值化处理。