[Insight-developers] itkOptMattesMutualInformationImageToImageMetric.txx question

[Danilchenko, Andrei Viktorovich]

Hello, developers.

I need some help understanding how
itkOptMattesMutualInformationImageToImageMetric.txx works. I need to know
the number of samples used for computing MI in GetValue() function. In
itkMattesMutualInformationImageToImageMetric.txx variable nSamples is used
for this purpose. But in
itkOptMattesMutualInformationImageToImageMetric.txx there is no such
variable. Logically, m_JointPDFSum should contain the number of samples
used to compute MI. Is that right?

I tried running a program using these two implementations of Mattes MI and
output nSamples and m_JointPDFSum. For the same images nSamples was about
6 000 000, but m_JointPDFSum was just about 40 000 (moreover, in some
cases it was not an integer). So, I guess my assumption that m_JointPDFSum
shows the number of samples used to compute MI is not right. In this case
could you give me a hint how to find this number?

Thanks,
Andrei.