Shadow Removal of Text Document Images by Estimating Local and Global Background Colors

Abstract

This paper proposes a simple yet effective method for removing shadows from text document images. Assuming that the document mainly contains texts, our method estimates the global and local background colors using statistical analysis of the whole image and local neighborhoods. By estimating the global and local background colors, we obtain the shadow map indicating the shadow ratio for each pixel. With the shadow map, a shadow-free image can be recovered by intrinsic decomposition. Experiments confirm that our method effectively removes the shadow of text document images regardless of the intensity, scope, and the number of shadows.