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IDProjectCategoryView StatusDate SubmittedLast Update
0010599ITKpublic2010-04-23 03:042010-04-28 13:01
Reporterlantiga 
Assigned Tolantiga 
PriorityhighSeveritymajorReproducibilityalways
StatusclosedResolutionfixed 
PlatformOSOS Version
Product VersionITK-3-18 
Target VersionFixed in Version 
Summary0010599: itkHessianRecursiveGaussianImageFilter does not behave correctly in scale-space for dimensions > 2
DescriptionThis bug was identified by Oleksandr Dzyubak.
When NormalizeAcrossScale is set to true, the response of itkHessianRecursiveGaussianImageFilter is not consistent in scale-space. See attached test for reproducing the error: by creating objects at different widths and same peak intensities and computing the Hessian at the same sigma, the response is different across scales, while it should stay the same.
The bug has been there since the introduction of the class, and it is severe as it makes scale-space Hessian-based filters (vesselness, etc) fail to work correctly in 3D.

The problem is related to the battery of extra smoothing filters in itkHessianRecursiveGaussianImageFilter (itkHessianRecursiveGaussianImageFilter.txx, line 64), that are created for dimensions 3 and greater.
In SetNormalizeAcrossScale, line 107, NormalizeAcrossScale is set to true for the derivative filters *and* for the smoothing filters. This is incorrect, since only derivative filters should have the flag turned on, since they are used to fill in the Hessian matrix with correct values in scale-space. If the flag is on in the extra smoothing filters, the integral of the kernel function is not 1, and the values of the Hessian end-up with extra-rescaling, leading to incorrect scaling in scale-space.

The solution to the bug is to remove the call to SetNormalizeAcrossScale( normalize ); for the smoothing filters in the battery.
TagsNo tags attached.
Resolution Date
Sprint
Sprint Status
Attached Filescxx file icon itkHessianRecursiveGaussianFilterScaleSpaceTest.cxx [^] (4,062 bytes) 2010-04-23 03:04

 Relationships

  Notes
(0020369)
lantiga (developer)
2010-04-23 03:06

 After talking to Jim Miller, both the fix and a new test are about to be committed.
(0020465)
Luis Ibanez (manager)
2010-04-28 13:01

 Luis to apply this patch to the ITK 3.18 branch...

 Issue History
Date Modified Username Field Change
2010-04-23 03:04 lantiga New Issue
2010-04-23 03:04 lantiga File Added: itkHessianRecursiveGaussianFilterScaleSpaceTest.cxx
2010-04-23 03:05 lantiga Assigned To => lantiga
2010-04-23 03:05 lantiga Status new => assigned
2010-04-23 03:06 lantiga Note Added: 0020369
2010-04-28 03:14 lantiga Status assigned => closed
2010-04-28 03:14 lantiga Resolution open => fixed
2010-04-28 13:01 Luis Ibanez Note Added: 0020465

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