Efficient Graph based image segmentation

A new version of previous program, support color image.

This is an implementation of [1]. The result is slightly different from website[1], because we apply adjacent neighborhood rather than K nearest neighborhood. The following is an example usage:
%complie:(only once)
GraphSeg_complie
%Read an image
img = imread('images\rice.jpg');
%segmentation
[L, contour] = graph_segment(img, 1, 3, 100);
%display result
subplot(2, 1, 1), imshow(img), title('original image'); subplot(2, 1, 2), imshow(label2rgb(L)),title('segmented result');

[1]Efficient Graph-Based Image Segmentation
Pedro F. Felzenszwalb and Daniel P. Huttenlocher
International Journal of Computer Vision, Volume 59, Number 2, September 2004
http://people.cs.uchicago.edu/~pff/segment/