You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: perimeter.m
    path of file: ./repos/matImage/matImage/imMinkowski
    
    the code of the file until where you have to start completion: function perim = perimeter(img, varargin)

    
function perim = perimeter(img, varargin)
%PERIMETER estimate perimeter of a structure
%
%   p = perimeter(img);
%   Compute estimation of perimeter of structure in image IMG, using a
%   discrete version of Crofton formula in 4 directions (horizontal,
%   verticval, and 2 diagonals) of image.
%   
%   p = perimeter(img, method);
%   Specifies the method to employ :
%   - 'local4' : create polygon around the structure, using 4 connectivity,   
%   and compute perimeter of piolygon. This usually gives a great
%   overestimation of the perimeter.
%   - 'local8' : create polygon using 8 connectivity, giving a smaller
%   overestimation.
%   - 'crofton' (default) : count intersections with discete lines in 4
%   directions (horizontal, vertical, and 2 diagonals), and uses Crofton
%   formula to estimate perimeter.
%   - 'crofton2' : uses only 2 orthogoanl directions to count
%   intersections. Works better for spheres, but not so good for others
%   figures.
%
%   TODO: there is a small biais for some configuration using 'crofton'
%   This concerne only config with type [1 0;0 1] or [0 1;1 0] : the
%   contribution of the diagonal line is not counted, leading to
%   underestimation of perimeter of thin structures.
%
%   
%   ---------
%
%   author : David Legland 
%   INRA - TPV URPOI - BIA IMASTE
%   created the 03/04/2005
%


method = 'crofton';
if ~isempty(varargin)
    method = varargin{1};
end