% function[out]=Rgb2XyzModel3(img,colorTrans);
% Input: img, an RGB image, size = rows*cols*3
%        colorTrans, a 9x3 linear transformation matrix from RGB
%        to XYZ space.
% Output: out, an XYZ image
%
% Uses colorTrans transformation matrix to transform input RGB
% values to CIE-XYZ values.
%

function[out]=Rgb2XyzModel3(img,colorTrans);

[rows,cols,colors]=size(img);
if(colors~=3) 
  error('ERROR(Rgb2XyzModel3): Input must be three color image!') 
end
img=reshape(img,rows*cols,3);
m2img=zeros(size(img,1),9);
m2img(:,1)=img(:,1);
m2img(:,2)=img(:,2);
m2img(:,3)=img(:,3);
m2img(:,4)=img(:,1).*img(:,2);
m2img(:,5)=img(:,2).*img(:,3);
m2img(:,6)=img(:,3).*img(:,1);
m2img(:,7)=img(:,1).*img(:,1);
m2img(:,8)=img(:,2).*img(:,2);
m2img(:,9)=img(:,3).*img(:,3);
out = colorTrans*m2img';
out = reshape(out',rows,cols,3);