[Insight-users] SubtractImageFilter - Modification

[Christian Werner]

Forget it. I had a typo. Maybe I just quit programming for today and 
finally take a rest... :)


Christian Werner wrote:
> Hi!
>
> I need a slightly modified version of the itkSubtractImageFilter that 
> caps the result at 0, such that all negative values will become 0 
> instead. I know I could do that with the actual SubtractImageFilter 
> followed by a ShiftScaleImageFilter, but it is important that this is 
> a one-pass filter since we are working with extremely large (up to 
> 1GB) data.
>
> I usually program in vtk and from time to time need some itk filters, 
> so I don't have much clue about how to do that. Since this tiny little 
> itzy bitzy special subtraction is the only thing I need and I don't 
> have the time to really dive into "How to program ITK Filters that 
> rock", I just looked at the code of the itkSubtractImageFilter. It 
> seemed as if I could achieve what I want with changing a single line. 
> I did that and replaced every occurence of "SubtractImageFilter" with 
> "SubtractImageFilter2" (where the '2' denotes that this is a specially 
> tailored, next-generation filter).
>
> Then the time came to test out that new filter. I included it just 
> like any other itk filter:
>
> #include "itkSubtractImageFilter2.h".
>
> The compiler had no problem with that (it finds this header). But when 
> trying to instantiate a SubtractImageFilter2:
>
> 130 typedef itk::SubtractImageFilter2<ImageType, ImageType, ImageType> 
> SubtractFilterType;
> 131 typename SubtractFilterType::Pointer subtractFilter = 
> SubtractFilterType::New();
>
> I get:
>
> /home/christian/programming/pv-plugins/IO/vtkMeasureObjects.cxx:130: 
> error: expected initializer before ‘<’ token
> /home/christian/programming/pv-plugins/IO/vtkMeasureObjects.cxx:131: 
> error: ‘SubtractFilterType’ has not been declared
>
> which indicates that there is no SubtractImageFilter2. If I simply 
> remove the "2" in the include and in line 130, everything is compiled 
> just fine.
>
> It seems more has to be done to announce a new itk Filter. I have 
> attached the filter.
>
> Any ideas?
>
>
> Best regards,
> Christian
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