Form frame line detection with directional single-connected chain

In this paper, a novel form frame line detection algorithm is proposed based on the directional single-connected chain (DSCC). Defined as an array of black pixel run-lengths, DSCC works very well as an image structure element or vector in our vectorization algorithm. By merging multiple DSCCs under some constraints, we are able to extract the form frame lines automatically yet fast. The speed of our algorithm is comparable with some well-known projection methods. Experiments show that our algorithm is fast, resistant to moderate serious line breaks and can detect diagonal lines with any angle.