whitebalance

http://www.doc88.com/p-20996826976.html理论和matlab实现

%Program for white balancing%
%Author : Jeny Rajan
%usage : W=imbalance(im) 
%im is the color image array to be corrected.
function W=wbalance(im)
im2=im;
im1=rgb2ycbcr(im);
Lu=im1(:,:,1);
Cb=im1(:,:,2);
Cr=im1(:,:,3);
[x y z]=size(im);
tst=zeros(x,y);
Mb=sum(sum(Cb));
Mr=sum(sum(Cr));
Mb=Mb/(x*y);
Mr=Mr/(x*y);
Db=sum(sum(Cb-Mb))/(x*y);
Dr=sum(sum(Cr-Mr))/(x*y);
cnt=1; 
for i=1:x
for j=1:y
b1=Cb(i,j)-(Mb+Db*sign(Mb));
b2=Cr(i,j)-(1.5*Mr+Dr*sign(Mr));
if (b1<(1.5*Db) & b2<(1.5*Dr))
Ciny(cnt)=Lu(i,j);
tst(i,j)=Lu(i,j);
cnt=cnt+1;
end
end
end
cnt=cnt-1;
iy=sort(Ciny,'descend');
nn=round(cnt/10);
Ciny2(1:nn)=iy(1:nn);
mn=min(Ciny2);
c=0;
for i=1:x
for j=1:y
if tst(i,j)<mn
tst(i,j)=0;
else
tst(i,j)=1;
c=c+1;
end
end
end
R=im(:,:,1);
G=im(:,:,2);
B=im(:,:,3);
R=double(R).*tst;
G=double(G).*tst;
B=double(B).*tst;
Rav=mean(mean(R));
Gav=mean(mean(G));
Bav=mean(mean(B));
Ymax=double(max(max(Lu)))/15;
Rgain=Ymax/Rav;
Ggain=Ymax/Gav;
Bgain=Ymax/Bav;
im(:,:,1)=im(:,:,1)*Rgain;
im(:,:,2)=im(:,:,2)*Ggain;
im(:,:,3)=im(:,:,3)*Bgain;
W=im;
figure,imshow(im2,[]),title('Original Image');
figure,imshow(im,[]),title('Corrected Image');

 

%%%%%输出

Mb =

117.6220

Mr =

131.1654

Db =

2.7661

Dr =

2.4683

Rav =

12.4033

Gav =

13.6090

Bav =

7.6074

Rgain =

1.2631

Ggain =

1.1512

Bgain =

2.0594