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

[Thomas Deschamps]

Thank you for your answer.
Could you tell me if the convention for morphological reconstructions is
always

FunctionName( SeedImage, MaskImage, optional parameters) ?

And is it the same for other routines like
MorphologicalWatershedFromMarkersImageFilter?
I could not find the answer in the documentation.

Thanks!


On Tue, May 21, 2013 at 3:01 AM, Richard Beare <richard.beare at gmail.com>wrote:

> 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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