[Insight-users] Anisotropic diffusion ( was RE: ShapeDetection)

[Lydia Ng]

Can someone help Christina as to the differences
in the differ favors of anisotropic diffusion?

She is hoping to use the anisotropic diffusion to remove
texture and enhance MR images of the liver.

Cheers,
Lydia

> -----Original Message-----
> From: Christina Lee [mailto:dreamie222@yahoo.com]
> Sent: Wednesday, March 20, 2002 2:28 PM
> To: Lydia Ng
> Subject: RE: ShapeDetection
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> Hi Lydia,
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> How are you?
> I think I'll try to preprocess the MR images with
> anisotropic diffusion as you suggested. Although I'm
> not exactly sure what kind of anistropic diffusion
> filter that I need (there seems to be three
> -curvature, gradient & vector!?)
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> I couldn't find the source code (or the cxx file) for
> itkAnisotropicDiffusionImageFilter.h & I did a
> thorough search on the files that I downloaded from
> the ITK website. Are there DLL or LIB files for the
> derived classes that I'm not aware of?=20
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> Hope to hear from you soon.
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> Thank you so much for your help!
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> Christina
> --- Lydia Ng <lng@insightful.com> wrote:
> > Hi Christina,
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> > The ShapeDetection program is not very sophisticated
> > in
> > that it only uses image gradient information to
> > generate
> > an edge potential map. Ideally, the edge potential
> > map is
> > zero at an "edge" and one in homogenous areas.
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> > A fastmarching algorithm is used to grow out
> > a contour from a seed point. The rate of expansion
> > of the=20
> > contour is determined by the values in the edge
> > potential map.=20
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> > I think the algorithm is working well for CT=20
> > because the edges are nice and strong.
> > I am not familiar with MR images of the liver, but
> > if there are
> > high gradient textures within the liver then these
> > might=20
> > interfere with the expansion of the contour.
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> > The other issue is that the computed edge potential
> > map
> > is far from ideal. For example, if the boundary
> > gradient isn't
> > strong, the associated edge potential will be
> > some non-zero value and the contour will eventually
> > leak=20
> > across the boundary as time goes on.
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> > What kind of output are you getting when you look
> > at it at various time crossing thresholds?
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> > I guess you can also try some preprocessing with
> > something
> > like anisotropic diffusion to get rid of some of the
> > texture
> > and enhance the boundaries.
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> > - Lydia
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> > > -----Original Message-----
> > > From: Christina Lee [mailto:dreamie222@yahoo.com]
> > > Sent: Wednesday, February 27, 2002 2:30 PM
> > > To: Lydia Ng
> > > Subject: ShapeDetection
> > >=20
> > >=20
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> > > Hi Lydia,
> > >=20
> > > How are you?=20
> > > I've been running the ShapeDetection program on
> > some
> > > MR images (to segment out the liver) & I haven't
> > had
> > > any luck. The program worked pretty well for the
> > CT
> > > data but not for the MR data - I wonder if it's
> > > because the MR images are more textured. Any
> > comments
> > > or suggestions?
> > >     =20
> > > Hope to hear from you soon.
> > >=20
> > > Thanks,
> > >=20
> > > Christina
> > >=20
> > > __________________________________________________
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