[Insight-developers] Re: design problem with VectorImage and ImageAdaptor ?

[Gaetan Lehmann]

On Wed, 08 Mar 2006 00:40:47 +0100, Karthik Krishnan  
<Karthik.Krishnan at kitware.com> wrote:

>
>
> Gaetan Lehmann wrote:
>
>>
>>> Is it fixed with this fix ?
>>> http://www.itk.org/cgi-bin/viewcvs.cgi/Code/Common/itkVectorImageToImageAda
>>> ptor.h?root=Insight&r1=1.7&r2=1.8
>>>
>>>
>>
>> Yes, it builds, with  typedef typename TImage::InternalPixelType  
>> InternalPixelType;
>>
>> in itkImageAdaptor.h, instead of  typedef typename  
>> TAccessor::InternalType InternalPixelType;
>>
>>
>>
> That would not work. The typedefs are not equivalent. The former is type  
> T. The latter is VariableLengthVector< T >

That's exactly why I have done this change, and at least, it builds now  
for the adaptor, and I can't see how that change can prevent the build of  
the ImageFileReader.

>
>> I'm using ITK 2.4.1. ITK cvs would solve that problem ?
>>
> ITK2-4-1 and CVS is probably in the same state for the wrappers for the  
> VectorImageToImageAdaptor class.

So there is currently nothing to do to use wrap those class?
Sadely in that case, that's not a wrapper problem, and it mean the code is  
broken.

>
>>> Not really. I was just an example. Since you've wrapped VectorImage and
>>> VariableLengthVector, it should generally suffice.
>>>
>>>
>>
>> How do you extract a normal image from a vector image without it ?
>>
>>
> Just an iterator. In fact, we've been forced to do this in most cases.
>
> Lines 291-315.  
> http://www.itk.org/cgi-bin/viewcvs.cgi/Code/Algorithms/itkBayesianClassifierImageFilter.txx?annotate=1.4&root=Insight
>   itrPosteriorImage is an iterator on a VectorImage.
>   extractedComponentImage is an extracted component.
>
> Here the intent was to smooth each component and Anisotropic diffusion  
> filters will not work on non-scalar images. Adaptors might help save  
> memory, but IMHO once you put them in a pipeline for a filter that works  
> on image regions, the price you pay for non-contiguous memory access  
> would outweigh it, (I think).
>

iterator or still not usable with wrappers, and it does fit well with the  
usage of VectorImage to read an image with several channels - it's just  
not usable in a pipeline.
I don't like too much adaptor, but it seem that the only class able to  
extract a scalar image from a VectorImage for now.
I guess I have to write a filter to extract the channel I'm interested in.  
It would also avoid the efficiency problem your talking about.

A more reasonable way seem to consider that VectorImage is not ready yet,  
and to split the channels in several files before processing images in ITK.
I hope it will be usable soon

Gaetan

-- 
Gaëtan Lehmann
Biologie du Développement et de la Reproduction
INRA de Jouy-en-Josas (France)
tel: +33 1 34 65 29 66    fax: 01 34 65 29 09
http://voxel.jouy.inra.fr