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: image2clusters.m
    path of file: ./repos/CanlabCore/CanlabCore/Cluster_contig_region_tools
    
    the code of the file until where you have to start completion: function varargout = image2clusters(varargin)
% Menu-driven function for getting clusters from an image file (e.g., a
% t-image)
%
% :Usage:

    
function varargout = image2clusters(varargin)
% Menu-driven function for getting clusters from an image file (e.g., a
% t-image)
%
% :Usage:
% ::
%
%    cl = image2clusters([overlay image name])
%
% Can also return clusters active in two contrasts, sorted by increases in
% both, decreases in both, inc in first, dec in first
% useful for testing whether something is both activated and correlated!
% e.g., see active_plus_corr_scatterplot_plugin
%
% % :Example:
% ::
%
%    [pospos,negneg,posneg,negpos] = image2clusters(overlay)
%
% ..
%    NOTE - documented usage does not appear to correspond to function
%    behavior - comment added by Jared 7/13/06
% ..


overlay = which('scalped_single_subj_T1.img');
if length(varargin) > 0 && ~isempty(varargin{1}), overlay = varargin{1};, end