If your actual goal is to normalize case so that you get Initial Caps, you probably want to use ucfirst and lc:

perl -le '@a=qw/capri cApRi TITLE-case/; for(@a){s/(\pL+)/ucfirst(lc $
+1)/ge; print}'
[download]

prints:

Capri
Capri
Title-Case
[download]

(The "\pL+" in the regex matches all "letter" characters; if your data tends to involve content in languages with non-Latin, non-cased letters, you'll probably want to use "\p{LC}" or "\p{CasedLetter}+" instead.)