[vtkusers] extend boundary of image

[Chen Fu]

Hi!
I recently compare the morphology operation in vtk,
itk and matlab. To my surprise, vtk and itk is much
slower than matlab. 
I believe the problem is the boundary processing. In
vtk and itk code, every pixel must take 8 compares to
confirm whether it is inside the image boundary. But
in matlab, the boundary is preprocessed by extending
the size of image, so get rid of such compares. I will
try to do some modify of vtk code to enhance its
performance, but i am not very clearly how to do
extend the image in vtk's pipeline architecture. 
Maybe somebody can give me some hints?


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Remote Scensing Satellite Ground Station
Chinese Academy of Science

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