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: imsmooth.m
    path of file: ./repos/2015_Face_Detection/vlfeat/toolbox/noprefix
    
    the code of the file until where you have to start completion: function varargout = imsmooth(varargin)
% VL_IMSMOOTH  Smooth image
%   J = VL_IMSMOOTH(I,SIGMA) convolves the image I by an isotropic

    
function varargout = imsmooth(varargin)
% VL_IMSMOOTH  Smooth image
%   J = VL_IMSMOOTH(I,SIGMA) convolves the image I by an isotropic
%   Gaussian kernel of standard deviation SIGMA.  I must be an array
%   of doubles. IF the array is three dimensional, the third dimension
%   is assumed to span different channels (e.g. R,G,B). In this case,
%   each channel is convolved independ