[Insight-users] EM with volumetric images in ITK

[Audette, Michel]

Hi all, 

I am looking for a method, or an example, for running Expectation Maximization with Gaussian Mixtures on a 3D image volume. The one example, on a 2D image, that I find seems to define a histogram from the image, then use the histogram elements to comprise a sample over which runs the EM method, but I dont think that this is correct...

  for ( unsigned int i = 0 ; i < histogramSize ; ++i )
    {
       sample->PushBack( histogram->GetFrequency( bin, 0 ) );//0 is for first channel
    }

I want to initialize the EM method with assistance from the histogram, but run EM with the actual data. 

If I use a sampling method looped over the 3 indices of the volume, the method seems to take a long time to run. Is there a way of using the input volume while limiting the complexity? 

Can anyone offer an example or suggestions? 

Best regards, 


Michel Audette, Ph.D. 
Innovation Center Computer Assisted Surgery (ICCAS) 
Philipp-Rosenthal-Strasse 55
Leipzig, Germany
Phone: ++49 (0) 341 / 97 - 1 20 13
Fax: ++49 (0) 341 / 97 - 1 20 09