[vtkusers] Questions on saving DICOM images

[iono sphere]

I am following offscreen image example
http://gdcm.git.sourceforge.net/git/gitweb.cgi?p=gdcm/gdcm;a=blob;f=Utilities/VTK/Examples/Cxx/offscreenimage.cxx;h=4545ee890ad6d6e95d4a2406f0ce3aed7db8f870;hb=HEAD

I tried play around with the code. I have successfully extract the image
from DICOM, however, I notice several things and want to ask the following:

1. The output image always have black unused area with the center of the
image being the DICOM image. Is there a way to tell VTK to crop the image
automatically? (remove the black area)

2. I set the vtkRenderWindow's size with renWin->SetSize(2048,2048); On
lower resolution, it works fine, but when I request for higher resolution
such as 2048 x 2048, why the output image is always 1284 x 1001? Is this the
max resolution possible?

Thank you.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.vtk.org/pipermail/vtkusers/attachments/20110206/90f816ea/attachment.htm>