[vtkusers] Drawing elements on an image

[qianc at ee.ethz.ch]

Dear all,
I have a very huge image, which is merged by hundreds of subimages  
from a microscope, and also an elements list (text file indicating  
elements' coordinates on the image). What I would like to do is  
drawing some markers on the image based on these coordinates. I guess  
it's sort of clear for me of how to draw on the image, but the problem  
is I would like to show the result in a rendered window. But I found  
it's too huge to be loaded (even if you do nothing but barely load  
it). My idea is: first process the image, write the result to an  
output image. then release all the memory and rescale the output  
image(into a lower resolution) and show it. Would this procedure be  
possible? I think I am stuck on how to release the memory, would  
anyone give some suggestion? Or some code examples would be very  
appreciate. Thanks in advance.
Best,
Cheng Qian