% I = imread('http://geo.fsv.cvut.cz/user/gin/git1/matlab/img/tree.jpg');
I = imread('../img/demo/tree.jpg');
R = I;   R(:,:,[2 3]) = 0;
G = I;   G(:,:,[1 3]) = 0;
B = I;   B(:,:,[1 2]) = 0;

figure(1),
subplot(3,3,2), imshow(I),
subplot(3,3,4), imshow(R),
subplot(3,3,5), imshow(G),
subplot(3,3,6), imshow(B),
subplot(3,3,7), imshow(mat2gray(R(:,:,1),[0 255])), 
subplot(3,3,8), imshow(mat2gray(G(:,:,2),[0 255])),
subplot(3,3,9), imshow(mat2gray(B(:,:,3),[0 255]));
%{
figure(2), imshow(I);
figure(4), imshow(R);
figure(5), imshow(G);
figure(6), imshow(B);
figure(7), imshow(mat2gray(R(:,:,1),[0 255])); 
figure(8), imshow(mat2gray(G(:,:,2),[0 255]));
figure(9), imshow(mat2gray(B(:,:,3),[0 255]));
%}