[Insight-users] About Level sets

[Luis Ibanez]

Hi Rashed,

                     Yes, it is possible.


Note that, for example, in FastMarching, *you* build the
speed image. Therefore, you can simply precompute the images:

    a) Gradient magnitude
    b) Vesselness

and combine them in any way you want to generate the speed image.
It seems, for example, that a multiplication of the two images will
produce the "AND" effect that you are looking for.


Then, finally, pass the computed speed image to the FastMarching
filter, as you have already seen it described in the ITK Software
Guide.


If you want to make a more sophisticated mixture of terms,
then you can easily write your own LevelSet filter, by still
reusing the ITK framework. In this case, you have to write
two classes:  X_LevelSetImageFunction and X_LevelSetImageFilter.
In this scenario, you will find useful to look at the code
implementing other LevelSet filters.


Also, since you are interested in Vessel segmentation, you may
find useful the following paper posted in the Insight Journal:


"Generalizing vesselness with respect to dimensionality and shape"
by Antiga, Luca
http://www.insight-journal.org/InsightJournalManager/view_reviews.php?back=search.php%3Ftexte%3Dvessel&journalid=9&pubid=175

	
"Vessel Enhancing Diffusion Filter"
Enquobahrie, Andinet; Ibanez, Luis; Bullitt, Elizabeth; Aylward, Stephen
http://www.insight-journal.org/InsightJournalManager/view_reviews.php?back=search.php%3Ftexte%3Dvessel&journalid=8&pubid=163



If you find these papers useful, you are strongly encouraged to
support OPEN ACCESS by posting reviews to the papers. Please note
that the reviews of the Insight Journal are not intended to be the
empty reviews of decadent traditional journals where the reviewers
simply speculate on what "they think" about the paper. On the contrary
the Insight Journal expects comments from fellow developers of image
analysis software who *actually* compiled and run the source code that
is accompanying the paper, and report on their experience on the use
of the code.



    Peer-review without reproducibility is mindless babbling.

    We already have had enough of that in our field...
    It is time to raise from the muddy waters of narcissism
    and move our field up to the standards of scientific work.



By the same token, If you find a way of integrating the two images
as input to your level set filter, you are also *strongly encouraged*
to submit your work as a paper to the Insight Journal. Here again,
papers to the Insight Journal are not about the childish quest for
"originality" claims that disgustingly plague the decadent journals
of our field. Instead, we expect your paper to demonstrate that the
practical solution that you found to your real image processing
problem, actually works. The demonstration is provided not by textual
arguments in your paper, but by the source code, parameters, images,
and instructions that you provide, describing how to *REPRODUCE* your
tests.


  Please let us know if you have any further questions,


     Thanks


        Luis



------------------
rashed karim wrote:
> Hi Everyone,
> 
> Is it possible to use the ITK level set implementations (such as Fast 
> marching, Geodesic, Laplacian, etc.) to drive a propogating front whose 
> speeds are governed by let's say two factors: 1. Gradient magnitude 2. 
> Frangi's vesselness. I want the propagating front to stop speeding at 
> points which give high responses to the vesselness filter AND have high 
> image gradient magnitudes.
> 
> Does ITK level set implementations allow users to define their own 
> criterion which limits the speed of the active contour? I have had a 
> good look at the ITK software guide, and it seemed like this isn't 
> possible.
> 
> Thanks in advance,
> 
> Regards,
> Rashed Karim
> 
> 
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