Canny detects edges in an image. This function detects relatively thick contours at the edge of bright regions.

Parameter

Description

Sigma

Degree of smoothing of input image before detection of edges. A Gauss filter is used as a smoothing function. The smoothing factor can be used to influence the sensitivity of recognition. If a low value is set, lots of edges are detected. Fewer edges are detected with a high value. If the value 0 is set, no smoothing is performed.

Threshold

Steepness of the edges to be detected. Low values mean "flat" edges with a wide transition area between two regions. In this case lots of edges are detected. If high values are used, fewer edges are detected, as only steep transition areas are interpreted as edges.