igraphseg

Graph-based image segmentation

L = igraphseg(im, k, min) is a graph-based segmentation of the color image im (HxWx3). L (HxW) is an image where each element is the label assigned to the corresponding pixel in im. k is the scale parameter, and a larger value indicates a preference for larger regions, min is the minimum region size (pixels).

L = igraphseg(im, k, min, sigma) as above and sigma is the width of a Gaussian which is used to initially smooth the image (default 0.5).

[L,nreg] = igraphseg(im, k, min, sigma) as above but nreg is the number of regions found.

Example

im = iread('58060.jpg');
[labels,maxval] = igraphseg(im, 1500, 100, 0.5);
idisp(labels)

Reference

"Efficient graph-based image segmentation", P. Felzenszwalb and D. Huttenlocher, Int. Journal on Computer Vision, vol. 59, pp. 167–181, Sept. 2004.

Notes

• Requires a color uint8 image.
• The hardwork is done by a MEX file in contrib/graphseg.
• With zero smoothing the number of regions can be massive and can crash MATLAB.

Author

Pedro Felzenszwalb, 2006.

See also

ithresh, imser

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