I've had good luck storing images in a PostgreSQL database using the bytea data type. Take a look at the bind_param section of DBD::Pg for more details on how to do it.

As a handy trick for pulling the images back out and displaying them without knowing the file extension, use File::MMagic to figure out the what kind of image it is. I used this to specify the header type on a CGI application that retrieved stored images.

However, if you're going to be storing a lot of images or speed is a concern, you're probably better off following amt's advice.