Open shape doesn't return the correct behavior

[davidAlgis]

When given in input, an open shape like a 'c' :

The algorithm find the contour of the shape on both "side" of the shape, therefore there are too many points:

The expected result will be to have just point on the path in this case as it already defined a contour.

[davidAlgis]

I solved it using the skeleton instead of the contour and the Visvalingam–Whyatt algorithm to retrieve just the important points