[Insight-users] Sorting watershed basins based on size

[SERIOT Rémi DEC/SPUA/LTEC]

Hi,

I would like to sort watershed basins based on size, so I need to calculate
the size of each basin from the labeled image. I need to do that and I don't
wont to re-invent something already done.
I think that I could use a simple ImageIterator and an accumulator for
compute the number of pixels in each basin from the labeled image and then
sort this list for keep only the most significant basins.

Could I speed it up this process with
itk::watershed::Segmenter::flat_region_t information ?

Or there is another way to do the same thing ?

After that could I have to change the EquivalencyTable ?

Thanks for your help
 
Rémi

> -----Message d'origine-----
> De : Joshua Cates [mailto:cates at sci . utah . edu]
> Envoyé : vendredi 13 juin 2003 18:05
> À : SERIOT Rémi DEC/SPUA/LTEC
> Cc : 'insight-users at public . kitware . com'
> Objet : RE: [Insight-users] How to create my own 
> NeighborhoodOperator ?
> 
> 
> Hi Rémi,
> 
> Glad to hear the NeighborhoodOperator is working out.
> 
> In order to sort and merge watershed basins based on size you 
> will have to
> modify the itkWatershedSegmenter algorithm to keep track of 
> basin sizes.  
> The initial size would need to be computed in the gradient 
> descent step of
> itkWatershedSegmenter and then updated and maintained during 
> basin merge
> operations.
> 
> An alternate approach of a one-time suppression of small basins in =
the
> initial output might be interesting (but will result in a different
> algorithm and I can't guarantee you won't get some 
> undesirable grouping of
> basins).  You could calculate the basin sizes from the the initial
> segmentation (zero merge level output) of the 
> WatershedSegmenter and then
> use some of the existing code for basin merges (in
> itkWatershedSegmentTreeGenerator, for example) to pre-merge 
> the smaller
> basins in the segment tree.
> 
> Josh.
> ______________________________
>  Josh Cates			
>  School of Computer Science	
>  University of Utah
>  Email: cates at sci . utah . edu
>  Phone: (801) 587-7697
>  URL:   http://www . sci . utah . edu/~cates
>