how to differentiate images

i have code for segmentation

   he = imread('without algae2.jpg');
  imshow(he), title('H&E image');
  text(size(he,2),size(he,1)+15,...
       'Image courtesy of Alan Partin, Johns Hopkins University', ...
       'FontSize',7,'HorizontalAlignment','right');
   cform = makecform('srgb2lab');
  lab_he = applycform(he,cform);

ab = double(lab_he(:,:,2:3));
nrows = size(ab,1);
ncols = size(ab,2);
ab = reshape(ab,nrows*ncols,2);

nColors = 2;
% repeat the clustering 3 times to avoid local minima
[cluster_idx, cluster_center] = kmeans(ab,nColors,'distance','sqEuclidean', ...
                                      'Replicates',3);

                                    pixel_labels = reshape(cluster_idx,nrows,ncols);
  imshow(pixel_labels,[]), title('image labeled by cluster index');
  segmented_images = cell(1,3);
  rgb_label = repmat(pixel_labels,[1 1 3]);

for k = 1:nColors
    color = he;
    color(rgb_label ~= k) = 0;
    segmented_images{k} = color;
end

imshow(segmented_images{1}), title('objects in cluster 1');
figure,imshow(segmented_images{2}), title('objects in cluster 2');

in this i have taken two clusters i want to find cluster which is in green colour,how ca i find green colour in the clustered image

i tried ranges for green color by setting threshold likE R<=100,G>200,B=0,but could not get result

I want to find if green colour is present r not in particuler cluster,kindly help,i have attached images

i have attached images wit and without green part in image kindly help