use strict;
my $str = 'image1
image2
image3
image4
image5
image6
image7
image8
image9
image10
image11
image12
image13
image14
image15
image100
image101
image102
image103
image104
image105';
my $regex = qr/image(\d\d)$/mp;
my $subst = 'image0$1';
my $result = $str =~ s/$regex/$subst/rg;
print "The result of the substitution is' $result\n";
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html