convert double into unit8 with out changing pixel's value

i want to change my image matrix which double type into uint8 type value so i can subtract another matrix which is uint8 type my code is

clc;
clear;
rgb = imread('flower.jpg');
rgb = imresize(rgb,[256,256]);
mlab = makecform('srgb2lab');
lab = applycform(rgb,mlab);

S_bin = im2bw(rgb);
S = S_bin + (S_bin == 0);
NS=S;
%[a,b,c] = size(lab);

L=lab(:,:,1);%figure(1);imshow(L);
A=lab(:,:,2);%figure(2);imshow(A);
B=lab(:,:,3);%figure(3);imshow(B);

k=1;
 for i=1:256
     for j=1:256
%        disp(i);
%        disp(j);

           m = region(i,j,lab);

         A1=m(:,:,2);
         B1=m(:,:,3);

         Amean = mean2(A1);
         Bmean = mean2(B1);

                L1=m(:,:,1);
              Lmean = mean2(L1);
              Lstd = std(L1);

          if Amean+Bmean<=256 
              if L <= (Lmean - (Lstd/3))
                  S(j,i,1)=0;
                 S(j,i,2)=0;
                 S(j,i,3)=0;
              else
                S(j,i,1)=L1;
                 S(j,i,2)=A1;
                S(j,i,3)=B1;
              end    

          else
               if L(i,j) < B(i,j)
                 S(j,i,1)=0;
                S(j,i,2)=A1;
                S(j,i,3)=B1;
               elseif B(i,j) < L(i,j)
                 S(j,i,1)=L1;
                S(j,i,2)=A1;
                S(j,i,3)=0;
               else
                 S(j,i,1)=L1;
                S(j,i,2)=A1;
                S(j,i,3)=B1;
              end

           end
           if(j==255)
               break;
           end
       end;
           if(i==255)
               break;
           end
   end;
  S1 = uint8(S);
  sub = imsubtract(rgb,S2);
  imshow(sub);

in above code rgb(type 256*256*3 uint8) is main image, S(type 256*256*3 double) is a image which is output image after doing some pixel operation now for subtracting image i have to convert one of them ,and make both of them same type image so i convert S into S1 but at here it changes pixel value of image which is affecting to main output so please ,give me solution to convert one of them and make both image as equal type but it should not change its value

[Image Analyst]

What is this code supposed to do? I've never seen anybody compare an L value to an A or a B value! What's up with that???? Also, what is S supposed to be? What does the region() function do?

[hardik mehta]

I am sorry for trouble sir,but my problem had been solved and thank you for you time. actually above problem is for detecting shadow from image . in that i had separated shadow pixel into another image and that image i want to subtract from original image .

Answer 1

[Walter Roberson]

double() the uint8 image instead of uint8() the double image.