You can't do it with mod_alias (Redirect by that name). But it is very easy in mod_rewrite, because all you have to do is constrain your redirects to file names ending in something other than jpg/gif etc. In fact most redirects should be constrained by ending-- usually / or html or equivalent. Saves work for the server, since humans rarely ask for images by name.
And now you can start poring over past threads in this Forum :) Do your page URLs end in html or php or similar, or no extension at all?