Editing Edge detection (section)

=== Connectivity of gradients without using (high) magnitude thresholds ===
This method finds connected set of pixels having a directional derivative magnitude larger than a fairly small threshold.<ref>{{Cite journal |last1=Pak |first1=Mesut |last2=Bayazit |first2=Ulug |date=2020-07-01 |title=Regional bit allocation with visual attention and distortion sensitivity |url=https://link.springer.com/article/10.1007/s11042-020-08686-z |journal=Multimedia Tools and Applications |language=en |volume=79 |issue=27 |pages=19239–19263 |doi=10.1007/s11042-020-08686-z |issn=1573-7721}}</ref> It considers only presence of gradients instead of strength of gradients. After applying a dramatically small threshold (i.e. 5), a binary image is obtained. The morphological opening operation and the morphological closing operation are applied to the binary image to close gaps. Then, the distance transform operation is applied to the binary image to clear the pixels far from the background, so blob-like shapes or other false labeled regions are deleted from the edge map.