It looks as though that code is highly geared towards extracting the content of powerpoint files and then manipulating them into Word. I could be wrong, but it sounds like it is of limited use for what you want to do.

From what I've read (ie. Untested), Powerpoint itself should be capable of exporting slides as images (definitely jpeg, and maybe png also.)

Take a look at Win32::PowerPoint.
On its own it won't be enough, but, you may be able to figure out how it interacts with PowerPoint through Win32::OLE in order to build your own module/code to simply "Save As" your powerpoint files as images. Then discard the slide images you don't need and keep the ones you want...

best of luck with it.