# Is the output of approxPolyDP(c) a subset of the input contour c?

I'm determining corner points using an approximated version of contour **c**, then try to find the index of the found corner in the original contour using **numpy.where()**.
But for some points no index can be found, meaning the point seems not to be in the original contour.

As I understand the underlying DP-algorithm, no new points are added, is that correct?

Cheers!