[Insight-users] BinaryErodeImageFilter - strange behaviour

[Gaetan Lehmann]

Hi Jens,

Can you tell us which ITK version you're using ? The implementation of 
BinaryErodeImageFilter have change in the 2.4 release

Regards

Gaetan

On Monday 02 January 2006 19:56, mailinglist at tus-wickrath.de wrote:
> Hi,
>
> the behaviour of the "itkBinaryErodeImageFilter" depending on the size of
> the StructuringElementSize is quite strange, and I am not sure if this
> might be a problem with the filter of with my application. I do use an
> BinaryBallStructuringElement with varying radius. While the filter works
> most of the times as expected, there is usually one stucturingelement-size
> inbetween, where the filter output is exactly like the input, although this
> result is obviously wrong. For example:
> The input (binary image) is of size 10x12, while the boundary lines/columns
> have only zero elements. Applying an structuring element with radius=3
> causes that only one pixel unequal zero remains of the input image.
> Performing an erosion with radius=4,5,6 or radius=8,9,10 on the same input
> image causes logicaly that the ouput image contains only zero values. But
> performing an erosion with radius=7 produces an output image which is equal
> with the input. The same happend by using an input image of size 37x25 and
> an structuring element with an radius of exactly 10.
>
> Following a code fragment which is supposed to show roughly the main
> algorithm pipeline (it is pretty much like the example within the ITK
> Software Guide):
>
> typedef itk::Image< unsigned int, 2 > BinaryMaskType;
> typedef itk::BinaryBallStructuringElement<unsigned int, 2>
> MorphStructuringElementType; typedef
> itk::BinaryErodeImageFilter<BinaryMaskType, BinaryMaskType,
> MorphStructuringElementType> ErodeFilterType;
>
> ErodeFilterType::Pointer binaryErode = ErodeFilterType::New();
> MorphStructuringElementType structuringElement;
> for(int radius = 1;  radius<15; radius++)
> {
>    binaryErode->SetInput( bbMask );
>    structuringElement.SetRadius(radius);
>    structuringElement.CreateStructuringElement();
>    binaryErode->SetKernel( structuringElement );
>    binaryErode->Update();
>    // Now analyze the ouput...
> }
>
> Thanks a lot!
> Jens.
> _______________________________________________
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> Insight-users at itk.org
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