use strict;
use warnings;

my @images = qw{a.png b.gif c.svg d.blah.jpg ..};

foreach (@images) {
     my $after_last_dot = (split (/\./,$_))[-1];
     $after_last_dot //= '';
     print ".",$after_last_dot,"\n";
}

__END__
.png
.gif
.svg
.jpg
.     <=might want something else here?