TMTOWDI - I'd be tempted to use a glob like you did but with a regex. I don't think you need to really use -e

my $pre="image";
my $post="jpg";
my @files=<$pre.*.jpg>;

@files=reverse sort @files;
#should work because you don't have image.10.jpg
#if you do have image.10.jpg, then you will need to use
#image.09.jpg for example

foreach (@files)
{
    next unless m/^$pre\.(\d)\.$post$/; #just to be sure
    rename_and_log($_, "$pre." . ($1 >= 8 ? 9 : $1+1) . ".$post\n");
}
[download]

Sorry it's not very readable, but it should work. I think.

Update: I like merlyn's solution better.

michael
the blue haired monk