Modify group label image - kmeans

I have an image on which i have performed kmeans to segment objects (red circles). The lowest number of clusters that was able to segment the circles that i require was 5. Now, i want to modify the group label image so that it has only 2 groups: one for the circles and the other for the rest of the image. How may i do this?

This is how i found that k=5 segments the image best:

E = imread('earthquakes1.jpg');
X=reshape(E,size(E,1)*size(E,2),size(E,3));
K=[2 3 4 5];
for i = 1:4
[Layer,Centers] = kmeans(double(X),K(i));
Y = reshape(Layer,size(E,1),size(E,2)); 
B = labeloverlay(E,Y);
subplot (2,2,i);
imshow(B) ;
caption  = sprintf('K = %d',i+1);
title(caption);
end

Answer 1

[Image Analyst]

I don't understand. Is that image the one called 'earthquakes1.jpg' -- and does it have the red circles already in it? Or is 'earthquakes1.jpg' the map image alone, but with red circles that you plotted over it in the overlay? If you plotted the red circles, you already know their coordinates.

If the circles are burned into the image you can find them with normalized cross correlation (demo attached) or with the Color Thresholder app on the Apps tab of the tool ribbon. However you will have trouble finding red blobs as separate circles if the circles are greatly overlapped.

[Vedefsa Den]

Thank you ImageAnalyst. Your direction towards the color thresholder app helped. And yes, the circles are burnt onto the map.