Assigning colors to segmented pictures in MATLAB - matlab

Question

I was dealing with color segmentation with MATLAB. I used k-means clustering based on this document and come this far codewise;
global imgRGB;
global imgLAB;
img = imgRGB;
cform = makecform('srgb2lab');
imgLAB = applycform(img, cform);
ab = double(imgLAB(:,:,2:3));
rows = size(ab,1)
cols = size(ab,2);
ab = reshape(ab, rows*cols, 2);
cluster = 5;
[idx center] = kmeans(ab, cluster, 'distance', 'sqEuclidean', 'Replicates', 5);
label = reshape(idx, rows, cols);
figure; imshow(label, []);
imgSeg = cell(5);
rgb_label = repmat(pixel_labels, [1 1 3]);
for k=1:cluster
color = img;
color(rgb_label ~= k) = 0;
imgSeg{k} = color;
end
figure;
imshow(imgSeg{1});
I take image as input that is why it is defined global.
For a colored image like the one in link, it produces the grayscale output.
I think it assigns gray tones as colors but I need to assign a color to each cluster. I mean not gray tone but a color. How can I achieve that?

Answer 1

You should use a different colormap for your figure, when displaying the labels directly.
Try:
figure;
imshow(label, []);
colormap( rnad(max(imgSeg{1}(:))+1, 3) ); % use random color map
However, if you wish to convert the pixel_labels to an RGB image (3 color channels per pixel), you want to use ind2rgb (instead of replicating the labels to all channels). Replace rgb_label = repmat(pixel_labels, [1 1 3]); with
rgb_label = ind2rgb(pixel_labels, rand(max(pixel_labels(:)),3));