function blockvarsum=blockimg(img1,img2,blockr,blockc)
[sizex sizey ]=size(img1);
bsx=sizex/blockr;
bsy=sizey/blockc;


z=1;
m=blockr;
for i=0:bsx-2
   l=1;
   for j=1:bsy-1
      
      Rimg(:,:,z)=img1(i*blockr+1:m,l:j*blockc);
      Gimg(:,:,z)=img2(i*blockr+1:m,l:j*blockc);
            
      z=z+1;
      l=l+blockc;
   end
   m=m+blockr;
end

stdR=zeros(1,z-1);
stdG=zeros(1,z-1);


for i=1:z-1
   stdR(i)=std2(Rimg(:,:,i));
   stdG(i)=std2(Gimg(:,:,i));
end
blockvarsum=abs(sqrt(mean(stdR.^2-stdG.^2)));