non-green extraction problem from image

Hello, I'm trying to extract non-green from images, however It fails and does not give me a proper result. Do you know the reason? Why does it result with non-proper image? Thanks a lot.

Please see below orjinal image and result, also my matlab code.

orjinal and segmented image:

my code:

al1 = imread('image');   

tex=single(al1);

%
r=single(al1(:,:,1));
g=single(al1(:,:,2));
b=single(al1(:,:,3));

ExGreen=2*g-r-b;
ExRed=1.4*r-g-b;
dev=imsubtract(ExGreen,ExRed);

% otsu thresholding

thres_level = multithresh(dev); % automatic thresholding
%b_w = im2bw(dev,thres_level);
seg_I = imquantize(dev,thres_level);

%
RGB = label2rgb(seg_I,'gray');

RGB2 = single(bwareaopen(RGB,1000)); 

% remove the only background
BW = RGB2(:,:,1); 
BW = uint8(imfill(BW,'holes'));
leaves_only = al1;
for a = 1:3

      leaves_only(:,:,a) = leaves_only(:,:,a).*BW;

end

figure;
axis off
title('RGB Segmented Image')
k=imfuse(al1, leaves_only,'montage'); 
imshow(k)

Answer 1

[Image Analyst]

Try the Color Thresholder app on the Apps tab.

Or else see my color segmentation tutorials in my File Exchange: http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A31862

Answer 2

[Image Analyst]

Try the attached m-file where I extract the non-green parts.

[mehmet oztu]

First I really appreciated for your help. I tried it, but I'm getting error, index exceeds matrix dimension. Even I resized the image, and reduce till 100px, result didnt change.

[mehmet oztu]

thanks Image Analyst, I found out a solution.

[Image Analyst]

You're welcome. I just came back here because I noticed you have not marked it as Accepted. Are we done now, or do you still need help?