[Insight-developers] strange background values and BinaryErodeImageFilter

[Gaetan Lehmann]

Hi,

I have modified FastIncrementalBinaryDilateImageFilter to implement an  
efficient binary erosion filter.

I'm not able to easily reproduce the way BinaryErodeImageFilter set the  
background value. In fact, it seems to be quite strange.
I have attached 3 files :
  + bw.png is the source image. There is 3 colors in it. The white is the  
foreground value for erosion while gray and black are
both background.
  + out-current.png is the result of a binary erosion with a circular  
kernel with a radius of 15
  You can notice that the eroded disk in the middle of the shape is grey  
while the others eroded pixels are black. Also, the 2
gray shapes in the top of the image are modified.
  + out-fast.png is the result of the same erosion with the modified  
FastIncrementalBinaryDilateImageFilter. The white shape is
the same (great !). All eroded pixels are black, shapes at the top of the  
image are not modified, and the gray disk is still
visible inside the white shape.

Can we use the second behavior for the binary erode image filter ? I find  
it really more consistent than the current behavior, and it should avoid  
to spend time to reproduce a quite strange behavior.

Regards,

Gaetan

-- 
Gaetan Lehmann <gaetan.lehmann at jouy.inra.fr>
Tel: +33 1 34 65 29 66
Biologie du Développement et de la Reproduction
INRA de Jouy-en-Josas (France)
Web: http://voxel.jouy.inra.fr
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