[Insight-users] Non-flat (function processing) structuring elements and defining elements outside the region of support

[Richard Beare]

Generating structuring elements from images is demonstrated in
kernelShape.cxx, in the consolidatedMorphology package (at least in
the version you get from darcs).

However all the structuring elements supported by this package are
"flat" (the SE type is called "FlatStructuringElement". This means
that an image can be used to define a funny shaped SE, but it will be
a mask kernel, not a grey level SE. So you can't do the ImageJ rolling
ball with this package. In theory the histogram method can be used to
accelerate non flat structuring elements, but we haven't bothered. The
only other non flat SE morphology tools I'm aware of in ITK are the
parabolicMorpholgy ones (available at the same darcs repo), which
implement some very specific structuring functions and probably aren't
what you want.

If you can describe the problem in more detail there may be some
alternatives that come to mind.

On Tue, Jun 23, 2009 at 11:58 PM, Neal R. Harvey<harve at lanl.gov> wrote:
> OK, so I have taken a look at the documentation for consolidated morphology
> and I still cannot find all the information I think
> I need for creating arbitrary non-flat (i.e. function-processing)
> structuring element for mathematical morphological operations
> in ITK. For instance, if I want to create my own structuring element that
> has a particular overall dimension (i.e. bounding
> box), but within that box there will be elements that I do not want to be
> part of the structuring element's region of support,
> how do I do this? What is the value that denotes that a position within an
> overall rectangular structuring element array is
> not within the structuring element's region of support. In the mathematics
> this would be -infinity. But, I haven't been able to
> ascertain how the structuring elements are formatted in the ITK realm. I
> have been very impressed with ITK so far and there
> are lots of methods available for creating commonly-used structuring
> elements, such as circles, annuli, etc. But, I want to
> be able to create arbitrary structuring elements of any shape, size and
> topography and I haven't been able to find the information
> that explains how to do this.
> Any assistance in this matter would be very much appreciated.
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