Graph-Based Image Segmentation demo

A program demonstrating the use and capabilities of a particular graph based image segmentation algorithm described in:

P. Felzenszwalb, D. Huttenlocher, "Efficient Graph-Based Image Segmentation"
International Journal of Computer Vision, Vol. 59, No. 2, September 2004

Sources:

https://github.com/opencv/opencv_contrib/blob/3.1.0/modules/ximgproc/samples/cpp/graphsegmentation_demo.cpp

Contents

Load image
Create object
Segment image
Show result

Load image

in = imread(fullfile(mexopencv.root(),'test','fruits.jpg'));
assert(~isempty(in), 'Failed to load input image');

Create object

gs = cv.GraphSegmentation();
gs.Sigma = 0.5;
gs.K = 300;
gs.MinSize = 100;

Segment image

cv.Utils.setUseOptimized(true);
cv.Utils.setNumThreads(8);

tic
out = gs.processImage(in);
toc

nb_segs = numel(unique(out(:)));
fprintf('%d segments\n', nb_segs);

Elapsed time is 0.157844 seconds.
116 segments

Show result

if false
    res = zeros([size(out) 3], 'double');
    res(:,:,1) = mod(double(out) * 0.618033988749895 + 0.24443434, 1.2) * 360;
    res(:,:,2) = 0.95;
    res(:,:,3) = 0.80;
    res = uint8(255 * cv.cvtColor(res, 'HSV2RGB'));
else
    out = double(out) + 1;
    res = label2rgb(out, jet(nb_segs), 'k', 'shuffle');
end
imshow(res)