From the documentation:

"The simplest way to install the libraries used by Imager is to install Strawberry perl.

You can then use either the bundled Imager, or install from CPAN."

Strawberry perl ships with a C compiler, build tools, stacks of commonly used modules and dependant libraries. If you're working on a Microsoft Windows platform and want to make life easy for yourself, use Strawberry perl. Example release notes detailing additional modules/libraries http://strawberryperl.com/release-notes/5.22.0.1-32bit.html.