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: spm_erode.m
    path of file: ./repos/malini/Codes/deconvolution - model/spm8
    
    the code of the file until where you have to start completion: function ima = spm_erode(varargin)
% Perform an erosion on an image (2D or 3D)
% It uses either the supplied kernel or a standard 6-connectivity kernel.
% FORMAT: ima = spm_erode(ima)
% or
% FORMAT: ima = spm_erode(ima,kernel)
%
% Input:
% ima    : 2 or 3D image
% kernel : (Optional) voxel values in ima are replaced by the 
%          minimum value in a neighbourhood defined by kernel.

    
function ima = spm_erode(varargin)
% Perform an erosion on an image (2D or 3D)
% It uses either the supplied kernel or a standard 6-connectivity kernel.
% FORMAT: ima = spm_erode(ima)
% or
% FORMAT: ima = spm_erode(ima,kernel)
%
% Input:
% ima    : 2 or 3D image
% kernel : (Optional) voxel values in ima are replaced by the 
%          minimum value in a neighbourhood defined by kernel.
%          The "standard" erosion operation (in 2D) is realised
%          using the kernel
%          0 1 0
%          1 1 1
%          0 1 0
%
% Output:
% ima    : Eroded image.
%
% The functionality of this routine has been modelled on the function
% imerode from the MATLAB Image processing toolbox. It doesn't (yet)
% have a support function such as strel to help the user to define
% kernels (you have to do it yourself if you want anything above
% 6-connectivty) and it doesnt do the clever structuring element
% decomposition that strel does (and imdilate uses). That should
% in principle mean that spm_erode is slower than imerode, but
% at least for small (typical) kernels it is actually more than
% twice as fast.
% The actual job is done by spm_dilate_erode.c that serves both
% spm_dilate.m and spm_erode.m
%__________________________________________________________________________
% Copyright (C) 2008 Wellcome Trust Centre for Neuroimaging

% Jesper Andersson
% $Id: spm_erode.m 4310 2011-04-18 16:07:35Z guillaume $


if exist('spm_dilate_erode','file')~=3 
   error('spm_dilate_erode.c not compiled - see Makefile');
end