[Insight-users] A problem of Sampling in the Mattes Mutual Information Registration

[Luis Ibanez]

Hi Caojie,

More detail on the parameter selection for MattesMutualInformation
is available in the Software Guide

   http://www.itk.org/ItkSoftwareGuide.pdf

Section 8.4.1, pdf-page 261.

You will find the following paragraph in pdf-page 262:

> The metric requires two parameters to be selected: the number of bins
> used to compute the entropy and the number of spatial samples used to
> compute the density estimates. In typical application, 50 histogram
> bins are sufficient and the metric is relatively insensitive to
> changes in the number of bins. 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.



Regards

   Luis


---------------------
曹杰 wrote:

> Hi,
>     This is my problem:
>     When I use the Mattes Mutual Information Metric to registrate,
> 
>     the fixedimage's size is 128*128*20----(PET),spacing is  (3.92,3.92,4.25) 
>     the movingimage's size is 512*512*20----(CT),spacing is  (0.98,0.98,4.25)
>     
>     How many sample points should I take to registrate?
> Since the fixedimage is PET images, and in each image the content of the image is a small part,most of the image is the background pixels whose intensities are 0 .   According to this situation,how many sample points should be the best
> and need I use the FixedImageMask? If using the mask,how many sample points should be taken?
>     Thank you!
>                                                       ITK user   Cao Jie
> 
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