Computes the length of the input region perimeter.
The operation computes the perimeter length of a region shape. Because regions are pixel-precise, the literal computation of the length of the region contour would lead to the overestimation of the diagonal edges. Therefore, the filter employs the following equation to approximate the result:
- sides denotes the number of pixel sides adjacent to the region background
- vertices is the number of turns to right during clockwise walk along the pixel sides of the region boundary
- a, b are constants defined as follows:
To compute the actual contour of the region, one can use RegionContours filter.
This filter is available on Basic Complexity Level.