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: vl_rgb2xyz.m
    path of file: ./repos/robotic_perception/Trafic_Sign_Recognition/code/vlfeat-0.9.20-bin/vlfeat-0.9.20/toolbox/imop
    
    the code of the file until where you have to start completion: function J=vl_rgb2xyz(I,ws)
% VL_RGB2XYZ  Convert RGB color space to XYZ
%   J=VL_RGB2XYZ(I) converts the CIE RGB image I to the image J in
%   CIE XYZ format. CIE RGB has a white point of R=G=B=1.0
%
%   VL_RGB2XYZ(I,WS) uses the specified RGB working space WS. The
%   function supports the following RGB working spaces:
%
%   * `CIE'    E illuminant, gamma=2.2
%   * `Adobe'  D65 illuminant, gamma=2.2
%
%   The default workspace is CIE.
%
%   See also: VL_XYZ2RGB(), VL_HELP().

% Copyright (C) 2007-12 Andrea Vedaldi and Brian Fulkerson.
% All rights reserved.
%
% This file is part of the VLFeat library and is made available under
% the terms of the BSD license (see the COPYING file).

    
function J=vl_rgb2xyz(I,ws)
% VL_RGB2XYZ  Convert RGB color space to XYZ
%   J=VL_RGB2XYZ(I) converts the CIE RGB image I to the image J in
%   CIE XYZ format. CIE RGB has a white point of R=G=B=1.0
%
%   VL_RGB2XYZ(I,WS) uses the specified RGB working space WS. The
%   function supports the following RGB working spaces:
%
%   * `CIE'    E illuminant, gamma=2.2
%   * `Adobe'  D65 illuminant, gamma=2.2
%
%   The default workspace is CIE.
%
%   See also: VL_XYZ2RGB(), VL_HELP().

% Copyright (C) 2007-12 Andrea Vedaldi and Brian Fulkerson.
% All rights reserved.
%
% This file is part of the VLFeat library and is made available under
% the terms of the BSD license (see the COPYING file).

[M,N,K] = size(I) ;

if K~=3
	error('I must be a MxNx3 array.') ;
end