Difference between numberofFixedImageSamples and numberofSpatialSamples

c.spanakis83 · September 19, 2021, 1:46pm

Hello I want to use Mutual Information (specifically Mattes’ Mutual Information) in order to align 2 medical images. However, I found that it has two methods:

SetNumberofFixedImageSamples (unsigned int num)
SetNumberofSpatialSamples (unsigned int num)

What is the difference between Spatial Sample and Fixed Image Sample and how do the above methods affect the calculation of Mutual Information?

dzenanz · September 20, 2021, 1:26pm

They are the same, one delegates to the other:

github.com

InsightSoftwareConsortium/ITK/blob/9961ccd672cb67ab2128390a49748104eb4459b6/Modules/Registration/Common/include/itkImageToImageMetric.h#L237-L247

    
      
          void
          SetNumberOfSpatialSamples(SizeValueType num)
          {
            this->SetNumberOfFixedImageSamples(num);
          }
          
          
SizeValueType
          GetNumberOfSpatialSamples()
          {
            return this->GetNumberOfFixedImageSamples();
          }