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: orthviews.m
    path of file: ./repos/CanlabCore/CanlabCore/@image_vector
    
    the code of the file until where you have to start completion: function cl = orthviews(image_obj, varargin)
% Orthviews display (SPM) for CANlab image_vector (or fmri_data, statistic_image) object
%
% *Usage:
% ::
%
%    orthviews(image_obj, varargin)
%
% :Optional Inputs:
%   **'posneg':**
%        input generates orthviews using solid colors, separated for positive- and negative-valued voxels.
%
%   **'largest_region':**
%        to center the orthviews on the largest region in the image
%
%   **'overlay':**
%        followed by name of anatomical image to use as underlay
%
%   **'unique':**
%        plot groups of contiguous voxels in different, unique colors
%        - autodetect feature turns this on when there are <300 unique
%        values, or for 'atlas' objects. See 'continuous' below to force continuous.
%
%   **'parcels':**
%        plot voxels with each unique value in a different color
%        useful for images in which values indicate parcel or network
%        membership
%        Default is 'unique' for <300 values, 'continuous' for more.  Use

    
function cl = orthviews(image_obj, varargin)
% Orthviews display (SPM) for CANlab image_vector (or fmri_data, statistic_image) object
%
% *Usage:
% ::
%
%    orthviews(image_obj, varargin)
%
% :Optional Inputs:
%   **'posneg':**
%        input generates orthviews using solid colors, separated for positive- and negative-valued voxels.
%
%   **'largest_region':**
%        to center the orthviews on the largest region in the image
%
%   **'overlay':**
%        followed by name of anatomical image to use as underlay
%
%   **'unique':**
%        plot groups of contiguous voxels in different, unique colors
%        - autodetect feature turns this on when there are <300 unique
%        values, or for 'atlas' objects. See 'continuous' below to force continuous.
%
%   **'parcels':**
%        plot voxels with each unique value in a different color
%        useful for images in which values indicate parcel or network
%        membership
%        Default is 'unique' for <300 values, 'continuous' for more.  Use
%        'unique' to force unique-valued colors.
%
%   **'continuous':**
%        Plot voxels color-mapped according to their values.
%        Default is 'unique' for <300 values, 'continuous' for more.  Use
%        'unique' to force unique-valued colors.
%
%   **'input_handle':**
%        followd by integer for which orthviews display to add to.
%        spm_orthviews can display multiple linked orthviews sections. If
%        you have initialized a display with multiple images, Enter 1 to
%        add to the first one, 2 for the second, and so forth.
%
%   **'add':**
%        Add to the first orthviews display (e.g., 'input_handle', 1)
%
%   **'color':**
%       Followed by cell with 3-element rgb vector,
%       e.g., 'color', {[1 0 1]}
%       This is superseded by 'unique' and 'posneg' options.
%
% ..
%    Copyright Tor Wager, 2011
% ..

% Aug 2017: Tor Wager edited to allow flexibility in colors; unique,
% parcel, continuous. and autodetect.

%overlay = which('SPM8_colin27T1_seg.img');
%overlay = which('keuken_2014_enhanced_for_underlay.img');
% overlay = which('fmriprep20_template.nii.gz');
overlay = canlab_get_underlay_image;

doposneg = false;
doreg = false;
input_handle=[];
dounique = false;
doparcels = false;
force_continuous = false;
additional_inputs = {};

for i = 1:length(varargin)
    if ischar(varargin{i})
        switch varargin{i}
            % reserved keywords
            case 'posneg',  doposneg = 1;

                % functional commands
            case 'overlay', overlay = varargin{i + 1}; varargin{i + 1} = [];

            case {'han', 'handle', 'input_handle'}, input_handle = varargin{i+1};

            case 'add', input_handle = 1;

            case {'largest_region', 'largest_cluster'}, doreg = 1;

            case 'unique'
                dounique = true;

            case 'continuous'
                force_continuous = true;

            case 'parcels'
                doparcels = true; dounique = true;

            case 'color'
                additional_inputs{end