A robust method for unknown forms analysis

This paper proposes a strategy for analyzing unknown, filled forms. First, horizontal and vertical line segments are detected, extracted and filtered. A recursive splitting and merging algorithm eliminates overlapping segments, filters false segments, and groups the segments into lines. Based on the extracted lines, an algorithm for rectangle extraction is proposed. We define the constraints between rectangles and edges. In a process of scanning the horizontal and vertical lines, candidate edges are validated and rectangles are generated if its surrounding edges and their combination are all valid. The process is recursively applied. It can tolerate large breaks in form lines, ignore irrelevant segments and deal with embedded rectangles. Experiments on a collection of forms show that our approach works well on poor quality images.