[vtkusers] pixel resolution reduction

[Jian Chen]

Hello,

I am trying to use software to simulate the effects of low resolution  
displays on a 9-monitor tilted stereo display. The original  
resolution is 800 x 600 x 9.  And I need to down sampling the image  
to 400x300x9.  I am using vtk-4.2.

I have tried to use opengl:

zoomFactor = 2;

glPixelZoom (zoomFactor, zoomFactor);
glViewPort(0,0,w/zoomFactor, h/zoomFactor);

glCopyPixels(0,0, w/zoomFactor, h/zoomFactor), GL_COLOR);

This worked but slowed down the program significantly.

Any suggestions on alternative ways to handle this problem? I am new  
to vtk. Any examples will be very helpful.

Thank you!
  - Jian