Editing Edge detection (section)

=== Phase congruency-based ===
A recent development in edge detection techniques takes a frequency domain approach to finding edge locations.  [[Phase congruency]] (also known as phase coherence) methods attempt to find locations in an image where all sinusoids in the frequency domain are in phase.  These locations will generally correspond to the location of a perceived edge, regardless of whether the edge is represented by a large change in intensity in the spatial domain.  A key benefit of this technique is that it responds strongly to [[Mach bands]], and avoids false positives typically found around [[roof edge]]s. A roof edge, is a discontinuity in the first order derivative of a grey-level profile.<ref>T. Pajdla and V. Hlavac (1993) "[https://link.springer.com/chapter/10.1007/3-540-57233-3_54 Surface discontinuities in range images]," in Proc IEEE 4th Int. Conf. Comput. Vision, pp. 524–528.</ref>