The original algorithm is from the paper: Doll´ar, P., and Zitnick, C. L. 2015. Fast edge detection using structured forests. IEEE transactions on pattern analysis and machine intelligence 37(8):1558–1570.
However, I also added a small edge enhancement algorithm on it.
The file edge-detection-algorithms.pdf contains a review paper of three edge detection and segmentation papers, and a detail of my implementation.