An Effective Background Estimation Method for Shadows Removal of Document Images

Shadows of document images bring about difficulties for digitization application and uncomfortable perception in vision. This paper proposes an effective method to remove shadows from the single document images, which contains two stages: shadow detection and shadow removal. For the shadow detection, an iterative neighboring information-based approach is designed to estimate pixel-wise local background color image, which can be used to generate a shadow map. For the shadow removal, a global reference background color is obtained from the local background color image. The shadow scale, which is applied to relight shadowed regions, can be estimated by local and global background color. Moreover, a tone fine-tuning process is designed to make the output colors be normal values. Experiments on document images indicate that the proposed method can produce high-quality unshad-owed document images with a comparable efficiency.