[vtkusers] Saving an image without a window (or display)

[Nicolas Clemeur]

Hello all,

I am a VTK beginner and for the moment I am playing with the
vtkXYPlotActor...

It seems quite easy to use and render it in a window. However, I would
like also to directly save the result in an image file, so that I can
run a script file to automatically generate images files (batch)
(without showing any window)

I have tried to use a Renderer without adding it to a RenderWindow, but
this does not seems to work...

Thanks for any hints,

Cheers

Nicolas