[Insight-developers] Problems with Variance in CannyEdgeDetectionImageFilter

[Bill Lorensen]

Brad,

I'll take a look. The warning in tkGaussianOperator.txx has been there
for a long time.

I do see changes to the baseline image for the
CannySegmentationLevelSetImageFilter that says
ENH: new baseline required after bug corrected in DiscreteImageFilter.

That was in ITK 3.0.

Looks like I made that change.

Bill

On Mon, Jun 2, 2008 at 12:59 PM, Bradley Lowekamp
<blowekamp at mail.nih.gov> wrote:
> I had a program which used larger values for the variance in the Canny edge
> filter algorithm. As I am updating the program to a newer version of the ITK
> library I had discovered that this is problematic with changes made in this
> algorithm. My observations can be observed with the Canny edge example
> program. With the following variance values I get the following:
>
> ~1 : good results
> ~2-4: warning of "itkGaussianOperator.txx", line 54 kernel being truncated.
> Results look plausible
> ~8+: the out put is an image full of nan (ugly!)
>
> Looking at the CVS, and knowing I was using ITK version 2.8.1 or 3.0 before.
> I am really not sure where this problem came from. Perhaps there was a
> change to DiscreteGaussianImageFilter?
>
> Any idea's why this class broke how I was using it?
> Also the method CannyEdgeDetectionImageFilter::SetMaximumError  has a small
> mistake in it.
> if (m_Variance[i] != v)
> should be:
> if (m_MaximumError[i] != v)
>
> Thank,
> Brad
>
> ========================================================
>
> Bradley Lowekamp
>
> Lockheed Martin Contractor for
>
> Office of High Performance Computing and Communications
>
> National Library of Medicine
>
> blowekamp at mail.nih.gov
>
>
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