Opening problem

[Emmanuelle Bourrat]

Dear all,

I have the following problem:

I'm using vtk3.1, and I'm trying to apply a vtkImageOpenClose3D. I have
a binary volume (black for the background and white for the object), and
I would like to open the object.


If I do the following:
vtkImageOpenClose3D *Open = vtkImageOpenClose3D::New();
	Open->SetInput(MyVolume);
	Open->SetKernelSize(2, 2, 2);
	Open->SetOpenValue(255.0);
vtkStructuredPointsWriter *writer - vtkSutrcutredPointsWriter::New();
 	writer->SetInput(Open->GetOutput);
	etc...
Then the ouput of the Open filter isn't different from its input.


And if I do:
vtkImageOpenClose3D *Open = vtkImageOpenClose3D::New();
	Open->SetInput(MyVolume);
	Open->SetKernelSize(2, 2, 2);
	Open->SetOpenValue(255.0);
	Open->SetCloseValue(0.0);
vtkStructuredPointsWriter *writer - vtkSutrcutredPointsWriter::New();
 	writer->SetInput(Open->GetOutput);
	etc...
Then the output of the filter is different, but I don't understand why I
should run an opening on the object and a closing on the background. 

Since opening the object should give the same result as closing the
background, is it necessary to run these 2 operations? Or is it
something I'm doing wrong?

Moreover, I also run an erosion filter (with vtkImageEDilateErode3D),
followed by a dilation filter on my volume, and the output of the
dilation filter is different from what I get in my second try.

Can anyone help we with this?

Thanks in advance,
Emmanuelle Bourrat.
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