Finding high intensity region by multiple histograms?

Dear Readers,

I have splitted an image into 4 parts, and calculated histograms for each image channel seprately, then drew it on single plotting figure. Is there any way to compare these multiple histograms and select the more intense region automatically from the input color image.Thqnks

clear all;
close all;
I=imread('trees.jpg');
subplot 331
imshow(I);
[r c p]= size(I);%r-rows,c-columns,p-planes
A=I(1:r/2,1:c/2,:);
B=I(1:r/2,c/2+1:c,:);
C=I(r/2+1:r,1:c/2,:);
D=I(r/2+1:r,c/2+1:c,:);
tic
subplot 332
imshow(A);
title('A');
subplot 333
imshow(B);
title('B');
subplot 334
imshow(C);
title('C');
subplot 335
imshow(D);
title('D');

subplot 336
      Red = A(:,:,1);
      Green = A(:,:,2);
      Blue = A(:,:,3);
      %Get histValues for each channel
      [yRed, x] = imhist(Red);
      [yGreen, x] = imhist(Green);
      [yBlue, x] = imhist(Blue);
      %Plot them together in one plot
      plot(x, yRed, 'Red', x, yGreen, 'Green', x, yBlue, 'Blue');
      title('Histogram of A ', 'FontSize', 8);
      
     subplot 337
      Red = B(:,:,1);
      Green = B(:,:,2);
      Blue = B(:,:,3);
      %Get histValues for each channel
      [yRed, x] = imhist(Red);
      [yGreen, x] = imhist(Green);
      [yBlue, x] = imhist(Blue);
      %Plot them together in one plot
      plot(x, yRed, 'Red', x, yGreen, 'Green', x, yBlue, 'Blue');
      title('Histogram of Cover B ', 'FontSize', 8); 
      
      subplot 338
      Red = C(:,:,1);
      Green = C(:,:,2);
      Blue = C(:,:,3);
      %Get histValues for each channel
      [yRed, x] = imhist(Red);
      [yGreen, x] = imhist(Green);
      [yBlue, x] = imhist(Blue);
      %Plot them together in one plot
      plot(x, yRed, 'Red', x, yGreen, 'Green', x, yBlue, 'Blue');
      title('Histogram of Cover C ', 'FontSize', 8);
      
      subplot 339
      Red = D(:,:,1);
      Green = D(:,:,2);
      Blue = D(:,:,3);
      %Get histValues for each channel
      [yRed, x] = imhist(Red);
      [yGreen, x] = imhist(Green);
      [yBlue, x] = imhist(Blue);
      %Plot them together in one plot
      plot(x, yRed, 'Red', x, yGreen, 'Green', x, yBlue, 'Blue');
      title('Histogram of Cover D ', 'FontSize', 8);
      toc;