% This function calculates the curvature of a 2D line.
% Reference：S. Hermann and R. Klette. Multigrid analysis of curvature estimators. Proc.
% Image Vision Computing New Zealand, 108–112, 2003.
% by Jianfei Pang
% k = CurvatureEstimation(list,b,f)
% list : A M x 2 list of line points.
% fn: The number of forward points that were chosen to calcute.
% bn: The number of backward points that were chosen to calcute.
% Ei : M x 1 Curvature values
% thetai:M x 1 angle values