clustering rgb image only green channel

Hello, i have image

i want to clustering only green channel from rgb image.

my code is :

I = imread('obraz1.png'); %%input image 

r = I(:,:,1);
g = I(:,:,2);
b = I(:,:,3);
I = g(:);%%green channel
I = ( I - min(I(:)) ) ./ ( max(I(:)) - min(I(:)) );    
I = ~I;

[m n]=size(I)
P = [];
for i=1:m    
    for j=1:n        
        if I(i,j)>0
            P = [P ; i j];        
        end
    end
end

size(P)
MON=P;   

[IDX,C]=kmeans(MON,3,'emptyaction','singleton')

 How do I display my output image?

Thanks for you help

Answer 1

[Image Analyst]

Tomas, since this normalizes (the badly-named) I into the range 0-1, and then you set I equal to the "inverse" what do you think that will do to the values of I. Check this out:

>> ~0.8
ans =
     0

So basically I is all zero.

[Tomas]

Ok, i want clustering only green channel, I do not have white background in input matrix

my other code :

I = imread('obraz1.png'); %%input image 

r = I(:,:,1);
g = I(:,:,2);
b = I(:,:,3);
H = g(:);%%green channel

[m n]=size(H)
P = [];
for i=1:m    
    for j=1:n        
        if H(i,j)<255
            P = [P ; i j];        
        end
    end
end

size(P)
MON=P;   

[IDX,C]=kmeans(MON,3,'emptyaction','singleton')

I do not know if that's good

[Image Analyst]

No, not really. For one thing, the whole loop can be replaced by

[rows, columns] = find(g < 255);

but even that won't do it because other colored spots might have green values less than 255. You have to find out the specific RGB value of the green spots you want to find so that you don't get other colors. Try calling impixelinfo() so you can mouse around on the image and see what colors the spots have. Or use imtool().

[Tomas]

I was lost, you can not tell me how I found out somehow automatically ?