Is it possible to reverse the stereo image of a stereo sound file?

If you mean change the left channel to the right channel and vice versa, you can do it with BIAS Peak Swap Channels.

try these:

http://www.smartelectronix.com/~mdsp/ms.php

A free set of VST plugs that do Mid-Side encoding, will separate the sides and middle of the stereo field for seperate processing.

Hope that helps.

TD