[Insight-users] itkSymmetricEigenAnalysisImageFilter

[Ruben Schilling]

Hi Jone,

If you are not going to implement it voxel-wise, but you would rather  
use the built-in image to image filter, then this might be of help to  
you:

typedef itk::FixedArray < double, dimension > EigenValueArrayType;
typedef itk::Image < EigenValueArrayType, dimension >  
EigenValueImageType;

You can get your eigen values then as an image by simply doing a
eigenFilter -> GetOutput ()
call to the eigen filter assigning it to an instance of the above  
eigen image type.

Regards,
Ruben


Am 24.08.2007 um 15:49 schrieb Patric:

> Ruben,
>
> Do you know how to access the eigenvalue after the  
> itkSymmetricEigenAnalysisImageF
> ilter is used?
>
> thanks,
> -Jone



Hi Karthik,


> I agree with you on the first point that there is no composite  
> filter to do all these operations in a memory efficient manner in  
> one filter, but these needs are so user specific.
>
> As far as a class to compute eigen values and vectors, it does  
> exist in ITK:
>
> See Common/itkSymmetricEigenAnalysis.h

Sorry, I overlooked, that this is not necessarily an image to image  
filter.


> The itkSymmetricEigenAnalysisImageFilter constructs a functor out  
> of this very class and applies it per pixel. It discards the eigen  
> vectors .. You could write your own functor, simply by replacing  
> the following line in itkSymmetricEigenAnalysisImageFilter.h
>
>       m_Calculator.ComputeEigenValues( x, eigenValues );
>
> with
>       m_Calculator.ComputeEigenValuesAndVectors( x,  
> eigenValues, ... );
>
> Regards
> --
> karthik

Regards,

Ruben
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