[Insight-users] Number of spacial samples Mattes MI metric

[jef vdmb]

Hi,

I am working on a 2D- 3D registration problem using the Mattes 
implementation of Mutual Information. One of the parameters to be set is the 
number of spacial samples. The Softwareguide says:

The number of spatial samples to be used depends on the content of the 
image. If the images are smooth and do not contain much detail, then using 
approximately 1 percent of the pixels will do. On the other hand, if the 
images are detailed, it may be necessary to use a much higher proportion, 
such as 20 percent.

Does this mean 1 or 20 percent of the total amount of pixels in BOTH images 
(fixed as well as moving)? This would mean a very high number of samples (~ 
30000 to ~800000).

Do I have to choose a number of histogram bins that is equally augmented?

Thanks you for any advice you can give me,

Jef