Troubles with ppm3d
 

Hello, everyone. I'm having a heck of a time using ppm3d (from the man page: "convert two portable pixmap into a red/blue 3d glasses pixmap") to produce anything useful-- indeed, anything but a terminal full of garble.

I enter "ppm left_ppm_file.ppm right_ppm_file.ppm" and get back several screens' worth of garbage. I'm sure that the inputs are, indeed, valid .ppm files; they are also of identical size. When it's all said and done, there is no new .ppm to be found.

I know that this is a very specialized program and an extremely obscure question (I'm good at that...), but any guidance would be greatly appreciated. Thanks very much in advance.