EdgeDetect uses radii in vertical and horizontal directions.
The Canny edge detection algorithm is used by default. With an explicit setting of the Method option, other derivative filters can be specified. Possible settings include:
first-order directional Gaussian derivatives
first-order derivatives of exponentials
binomial generalization of Sobel masks
An option setting "StraightEdges"->s can be used to control the selection of edges based on their straightness. With the default setting , all edges are returned. A setting selects only the longest and strongest lines.