[vtkusers] Writing image files

[Gib Bogle]

> I can create BMP and TIFF files, but with essentially identical code the 
> program crashes while executing writer->write() using vtkPNGWriter and 
> vtkJPEGWriter. The failure message (Windows XP) is the cryptic 
> "ABM_GUI.exe has encountered a problem and needs to close.  We are sorry 
> for the inconvenience."  I can see that the crash occurs when the 
> write() is executed.

I discovered that this error was the result of my oversight - I had in my PATH a 
directory with earlier VTK libraries.  All OK now.