1 View Code 
 2  %Program for white balancing%
 3  %Author : Jeny Rajan
 4  %usage : W=imbalance(im) 
 5  %im is the color image array to be corrected.
 6  
 7  function W=wbalance(im)
 8  im2=im;
 9  im1=rgb2ycbcr(im);
10  Lu=im1(:,:,1);
11  Cb=im1(:,:,2);
12  Cr=im1(:,:,3);
13  [x y z]=size(im);
14  Ciny = zeros(1,x*y);
15  tst=zeros(x,y);
16  Mb=sum(sum(Cb));
17  Mr=sum(sum(Cr));
18  Mb=Mb/(x*y);
19  Mr=Mr/(x*y);
20  Db=sum(sum(Cb-Mb))/(x*y);
21  Dr=sum(sum(Cr-Mr))/(x*y);
22  cnt=1;  
23 
24  for i=1:x
25      for j=1:y
26           b1=Cb(i,j)-(Mb+Db*sign(Mb));
27           b2=Cr(i,j)-(1.5*Mr+Dr*sign(Mr));
28          if (b1<(1.5*Db) && b2<(1.5*Dr))% & changed
29              Ciny(cnt)=Lu(i,j);
30              tst(i,j)=Lu(i,j);
31              cnt=cnt+1;
32          end
33      end
34  end
35  Ciny(cnt:end) = [];  
36   cnt=cnt-1;
37   iy=sort(Ciny,'descend');
38   nn=round(cnt/10);
39   Ciny2(1:nn)=iy(1:nn);
40   mn=min(Ciny2);
41   c=0;
42   for i=1:x
43       for j=1:y
44           if tst(i,j)<mn
45               tst(i,j)=0;
46           else
47               tst(i,j)=1;
48               c=c+1;
49           end
50       end
51   end
52   R=im(:,:,1);
53   G=im(:,:,2);
54   B=im(:,:,3);
55   R=double(R).*tst;
56   G=double(G).*tst;
57   B=double(B).*tst;
58   Rav=mean(mean(R));
59   Gav=mean(mean(G));
60   Bav=mean(mean(B));
61   Ymax=double(max(max(Lu)))/15;
62   Rgain=Ymax/Rav;
63   Ggain=Ymax/Gav;
64   Bgain=Ymax/Bav;
65   im(:,:,1)=im(:,:,1)*Rgain;
66   im(:,:,2)=im(:,:,2)*Ggain;
67   im(:,:,3)=im(:,:,3)*Bgain;
68   W=im;