[Insight-users] itk/simpleitk differences for ReconstructionByDilationImageFilter marker/mask inputs?

[Richard Beare]

Yes, it is unclear. I always end up getting it wrong even though I wrote
the current version. FYI, the requirement is not really necessary for the
current implementation, and was kept for compatibility with the original
(slow) version. My preference would be to produce a marker that was the
pixelwise min of the marker and mask, hence avoiding this issue. Also note
that it is the Vincent algorithm that is being used.

It is possible that the error message is back to front. For a
reconstruction by dilation the marker should be <= mask.

The convention is that the Marker image is dilated, and then masked by the
mask image, so the marker is the one that needs to be <= for a
reconstruction by dilation. In the opening by reconstruction the marker is
an eroded version of the original (always <= original) and the mask is the
original.




On Tue, May 21, 2013 at 4:35 PM, Thomas Deschamps <tdeschamps at lbl.gov>wrote:

> Hi
>
> In ITK ReconstructionByDilationImageFilter it's specifically written in
> the documentation<http://www.itk.org/Doxygen/html/classitk_1_1ReconstructionByDilationImageFilter.html>that The marker image must be less than or equal to the mask image (on a
> pixel by pixel basis).
> But in SimpleITK I get the following error message with
> sitk.ReconstructionByDilationImageFilter:
>
> itk::ERROR: ReconstructionByDilationImageFilter(0x7fd6fc671ea0): Marker
> pixels must be >= mask pixels.
>
>
> So either the message means that some marker pixels have been found to be
> >= to mask pixels, or another convention as been chosen. Does anybody know
> the answer?
>
> BTW, it is clearly not indicated in the documentation which image is the
> marker image and which one is the mask image. Is this documented anywhere?
>
> Thanks for your help.
>
> TD.
>
>
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