[Insight-users] ExtractImageFilter

[Luis Ibanez]

Hi Zein,

You are not calling "Update()" in the extract image filter.
The method "GenerateOutputInformation()" is called internally
as part of the update process.

Please call "Update()" instead of "GenerateOutputInformation()".

----


You may also want to try the RegionOfInterestImageFilter
instead of the ExtractImageFilter

http://www . itk . org/Insight/Doxygen/html/classitk_1_1RegionOfInterestImageFilter . html


The ExtractImageFilter is maintaining the
original settings for the LargestPossibleRegion
of the image, which tends to confuse filters
down the pipeline.

Please look at the example


   Insight/Examples/IO/ImageReadExtractWrite.cxx


This is discussed in the SoftwareGuide

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

Section 6.4 "Extracting regions", pdf-page 164.



Regards


   Luis




----------------------
salah wrote:
> Hello everybody,
> 
> I have used the ExtractImageFilter as shown in the piece of
> code bellow.
> 
> I expect the   "m_ExtractedImage"  to be a new image with
> the new dimensions (new size).  Actually, it is not. when 
> I view it, it is jsut the original input image!!!!
> 
> Could anybody please tell me if my code is principally correct???
> 
> Thanks,
> Zein
> 
> --------------------------------------------------------------------------------------------------
> 
> 
> /////// my code 
>    typedef  itk::ExtractImageFilter<InputImageType, InputImageType >     ExtractImageFilterType;
>    typedef  InputImageType::IndexType IndexType;
>    typedef  InputImageType::SizeType  SizeType;
> 
>    ExtractImageFilterType::Pointer  m_ExtractImageFilter = ExtractImageFilterType::New(); 
> 
>    IndexType start;
>    SizeType  size;
>  
>    start[0] = static_cast<IndexType::IndexValueType>( (int)xStart );
>    start[1] = static_cast<IndexType::IndexValueType>( (int)yStart );
>    start[2] = static_cast<IndexType::IndexValueType>( (int)zStart );
> 
>    size[0] = static_cast<SizeType::SizeValueType>( (int)xEnd - start[0] +1);
>    size[1] = static_cast<SizeType::SizeValueType>( (int)yEnd - start[1] +1);
>    size[2] = static_cast<SizeType::SizeValueType>( (int)zEnd - start[2] +1);
> 
>    InputImageType::RegionType region;
>    region.SetIndex( start );
>    region.SetSize( size );
> 
>    m_ExtractImageFilter->SetExtractionRegion( region );
>    m_ExtractImageFilter->GenerateOutputInformation();
>    m_ExtractedImage = m_ExtractImageFilter->GetOutput();
> 
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