function R=gray2rgb(img1,img2)
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%This Program converts a gray image ro RGB image based on the colors of the destination image. The better the destination image match with the source %
%gray image, the better the coloring will be. The program takes some time as the searching time is high. You can decrease the searching time by taking %
%only samples from the used color image but quality may decrease. U can use jittered sampling for improving running speed. %
% %
% You can use also use the attahed test images, Use the following combinations for better result nature1.jpg(as img1) and nature2.jpg(as img2) or %
% test1.jpg(as img1) and test2.jpg (as img2)
% %
% %
% Usage %
% gray2rgb('nature1.jpg','nature2.jpg');
%
% %
% Authors : Jeny Rajan %
% Chandrashekar P.S %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% img1 - Source Image (gray image)
% img2 - Selected color image for coloring the gray image.
tic
clc;
warning off;
imt=imread(img1);
ims=imread(img2);
[sx sy sz]=size(imt);
[tx ty tz]=size(ims);
if sz~=1
imt=rgb2gray(imt);
end
if tz~=3
disp ('img2 must be a color image (not indexed)');
else
imt(:,:,2)=imt(:,:,1);
imt(:,:,3)=imt(:,:,1);
% Converting to ycbcr color space
nspace1=rgb2ycbcr(ims);
nspace2= rgb2ycbcr(imt);
ms=double(nspace1(:,:,1));
mt=double(nspace2(:,:,1));
m1=max(max(ms));
m2=min(min(ms));
m3=max(max(mt));
m4=min(min(mt));
d1=m1-m2;
d2=m3-m4;
% Normalization
dx1=ms;
dx2=mt;
dx1=(dx1*255)/(255-d1);
dx2=(dx2*255)/(255-d2);
[mx,my,mz]=size(dx2);
%Luminance Comparison
disp('Please wait..................');
for i=1:mx
for j=1:my
iy=dx2(i,j);
tmp=abs(dx1-iy);
ck=min(min(tmp));
[r,c] = find(tmp==ck);
ck=isempty(r);
if (ck~=1)
nimage(i,j,2)=nspace1(r(1),c(1),2);
nimage(i,j,3)=nspace1(r(1),c(1),3);
nimage(i,j,1)=nspace2(i,j,1);
end
end
end
rslt=ycbcr2rgb(nimage)
figure,imshow(uint8(imt));
figure,imshow(uint8(rslt));
R=uint8(rslt);
toc
end
