Instance Aware Document Image Segmentation using Label Pyramid Networks and Deep Watershed Transformation

Segmentation of complex document images remains a challenge due to the large variability of layout and image degradation. In this paper, we propose a method to segment complex document images based on Label Pyramid Network (LPN) and Deep Watershed Transform (DWT). The method can segment document images into instance aware regions including text lines, text regions, figures, tables, etc. The backbone of LPN can be any type of Fully Convolutional Networks (FCN), and in training, label map pyramids on training images are provided to exploit the hierarchical boundary information of regions efficiently through multi-task learning. The label map pyramid is transformed from region class label map by distance transformation and multi-level thresholding. In segmentation, the outputs of multiple tasks of LPN are summed into one single probability map, on which watershed transformation is carried out to segment the document image into instance aware regions. In experiments on four public databases, our method is demonstrated effective and superior, yielding state of the art performance for text line segmentation, baseline detection and region segmentation.