#! perl -sw
use strict;

my @filespecs = map{ $_ =~ s/^(.*?)(\.\w*)$/my $temp = $2; ($_ = $1) =~ s!\W!_!g; $_ .= $temp/e; $_} <DATA>;

print $_, $/ for @filespecs;

__DATA__
me~swimming.jpg
J.R,ewing.jpg
A¬!£$%^&*()-_+={}[]'@;:~\#\"<>,./|\?.jpg
pic.