I guess this must be possible with a framescript but, as John pointed out, someone is going to have to create a "mapping table" with the old and new file names of the graphics. I wouldn't have the patience to do this for 300 graphics.
And, like Vijay said, does the reason for renaming the graphics justify the effort it will take? You can easily create a hyperlinked list of imported graphics in FrameMaker and there are a lot of (free) "image viewers" available to find and manage your graphics. Kind regards -- Yves Barbion ? Managing Director Scripto ? Adobe-Certified FrameMaker Instructor www.scripto.nu