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

[Neal R. Harvey]

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.