[Insight-users] Cost function value over a region

[Luis Ibanez]

Hi Martin,

Thanks for letting us know that you were using the
NormalizedMutualInformation class

http://www.itk.org/Insight/Doxygen/html/classitk_1_1NormalizedMutualInformationHistogramImageToImageMetric.html

Unfortunately this Metric is not taking the ImageMask
into account yet, and it is not counting the number
of pixels used either.

However, this can be added to the metric in its superclass
the HistogramImageToImageMetric class

http://www.itk.org/Insight/Doxygen/html/classitk_1_1HistogramImageToImageMetric.html


Please log a bug entry for this issue in the bugtracker

      http://www.itk.org/Bug/

and classify it as a "Feature Request".


Let us know if you encounter any difficulty creating your
account on the bug tracking.

In the meantime, you may want to give it a try to the other
two implementations of Mutual Information. In particular to
Mattes which is known to be easier to optimize.


     Regards,


        Luis



-------------------
Martin Kavec wrote:

> Hi Luis,
> 
> On Mon, 20 Dec 2004, Luis Ibanez wrote:
> 
> 
>>Hi Martin,
>>
>>
>>Some questions:
>>
>>
>>A)  What "GetNumberOfPixels()" method are you exactly calling ?
>>     I don't think there is a method with this name on the
>>     Image metrics...
> 
> 
> Sorry, I didn't have very good Internet connection at a time of writing to
> check exactly the name of function. I used virtual function called
> "GetNumberOfPixelsCounted"
> 
> http://www.itk.org/Doxygen/html/classitk_1_1ImageToImageMetric.html#a9
> 
> 
>>
>>B)  The number of samples used shouldn't be the full number
>>     of pixels in the image. That will be a killer for the
>>     performance of the metric. The number of samples should
>>     be in the range of 2%-10% of the total number of pixels.
>>
>>
>>C)  What specific implementation of Mutual Information are you using ?
>>     There are 4 of them in ITK:
>>
>>        - Viola & Wells
>>        - Mattes
>>        - KullbackLiebler
>>        - NormalizedMutualInformation
> 
> 
> I use NormalizedMutualInformation.
> 
> 
>>http://www.itk.org/Insight/Doxygen/html/group__RegistrationMetrics.html
>>
>>
>>
>>
>>Please let us know,
>>
>>
>>
>>   Thanks
>>
>>
>>
>>      Luis
> 
> 
> Cheers,
> 
> Martin
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