% HCI colour fusion 
% written by Stavri Nikolov (stavri.nikolov@bristol.ac.uk), University of Bristol, UK 

% directory containing the input images
dirname='c:\testimages\';

% input images. e.g 
% high-resolution spot image
fname1='denver-spot.bmp';
% and low-resolution landsat image
fname2='denver-landsat.bmp';
% note: this is just an example and the test images are not 
% provided with this script

% load input images
[im1,map1]=imread([dirname fname1],'bmp');
[im2,map2]=imread([dirname fname2],'bmp');

% convert index images to rgb images
rgbim1=ind2rgb(im1,map1);
rgbim2=ind2rgb(im2,map2);

% convert second rgb image to hsv
hsvim2 = rgb2hsv(rgbim2);

% replace it's value/intensity channel with that of the first image
hsvim2(:,:,3)=rgbim1(:,:,3);

% convert back from hsv to rgb 
hsvim = hsv2rgb(hsvim2);

% show the hsi fused image
imshow(hsvim);

% and save it
imwrite(hsvim,[dirname 'denver-hsv-fusion.bmp'],'bmp');