[Insight-users] Re: itkNormalizedMutualInformationHistogramImageToImageMetric

[Grace Chen]

Hi there,

Can anyone tell me if this metric value goes down, does it indicate worse result?  


Grace
  ----- Original Message ----- 
  From: Grace Chen 
  To: insight-users at itk.org 
  Sent: Wednesday, June 21, 2006 11:59 AM
  Subject: itkNormalizedMutualInformationHistogramImageToImageMetric


  Hi there,

  I tried looking for examples on how to set this metric up properly, however, none seem to work well.... The way I am setting this metric is shown below.  However, it gives rediculously bad result. And it's super slow.  To register two volume, what it used to take (when I use itkMattesMutualInformationImageToImageMetric) was 30 sec and now it's taking 10 mins or more....
  And also, the metric value starts from 1.2 to 1.006.  

  Does anyone know what's going on?  Or does anyone know how to set this metric up proerply??

  Grace

  ------------------------------------------------------------------------------------
  unsigned int nBins = 32;

  MetricType::HistogramType::SizeType histSize;

  histSize[0] = nBins;

  histSize[1] = nBins;

  metric->SetHistogramSize(histSize);


  // Plug the images into the metric.

  metric->SetFixedImage(fixedImage);

  metric->SetMovingImage(movingImage);

  const unsigned int numberOfParameters = transform->GetNumberOfParameters();

  typedef MetricType::ScalesType ScalesType;

  ScalesType scales( numberOfParameters );

  scales.Fill( 1.0 );

  metric->SetDerivativeStepLengthScales(scales); 

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