[Insight-developers] DiffusionTensor3DReconstructionWithMaskImageFilter enhancement question.

[Williams, Norman K]

I am in the process of adding a mask input to itk:DiffusionTensor3DReconstructionWithMaskImageFilter.

Currently, there is a threshold parameter, so that it ignores voxels in the reference image with values below the threshold.  What I'm adding is some code at the same point to look up the corresponding voxel in a mask image.

The problem is that at that point in the filter, it's stepping through the image with an ImageRegionConstIterator.  I could use an ImageRegionConstIterator to step through the mask at the same time, but the filter can't no for a fact that the mask and the reference image are congruent in space.  So I'm doing this:

        ItIndexType index(it.GetIndex()); // get index from reference image iterator
        MaskImageType::PointType pt;
        refImage->TransformIndexToPhysicalPoint(index,pt); // find physical point for index

        MaskImageType::IndexType maskIndex; // find index in mask from physical point
        this->m_MaskImage->TransformPhysicalPointToIndex(pt,maskIndex);
        MaskImageType::PixelType pix =
          this->m_MaskImage->GetPixel(maskIndex);

This seems to be the right thing to do, but it has to add considerable overhead compared to a ImageRegionConstIterator. Is there a better way to do this?



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