[Insight-users] Watershed plateau problem

[Joshua Cates]

Hi Aymeric,

Yes the ITK watersheds implementation is not morphological watersheds as
you describe so if you need that particular algorithm it will have to be
implemented separately.  You may be able to reuse some of the components
of the existing watershed filter.

In our experience thus far with the ITK implementation and medical images,
we have found that plateaus typically only result when the edge image used
as input to the watershed filter is thresholded.  In other words, we only
find plateaus that we artificially create in the data.  This makes them
less of an issue because any such thresholding is usually done to remove
low, background values.


Josh.

______________________________
 Josh Cates			
 School of Computer Science	
 University of Utah
 Email: cates@sci.utah.edu
 Phone: (801) 587-7697
 URL:   http://www.sci.utah.edu/~cates


On Mon, 19 May 2003, Aymeric Perchant wrote:

> Having read the fabulous InsigthSoftwareGuide.pdf I discovered that the
> watershed implementation was a "top down", "steepest gradient descent"
> implementation that works well on float, or even color images.
> 
> A morphological watershed on a binary image should be a skiz (skeleton
> by influence zone). The ITK watershed does not have this feature. The
> real problem is that it does not behave well on plateaus : a given
> plateau in an image can only belong to one segment. Whereas it should be
> split according to what nearest minima a pixel belong to.
> 
> How can I adress this plateau problem with itk ? Do I have to write a
> morphological watershed, like the one Vincent & Soille proposed (IEEE
> PAMI, Vol 13 No 6, june 1991 : Watershed in digital spaces: An efficient
> algoritm based on immersion simulations) ?
> 
> Thanks,
> 
> 
> Aymeric Perchant
> 
> 
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