[PHP] sample code snippets writing text to images?

[Kurt Lieber]

I'm learning how to work with images in PHP and specifically learning
how to write text dynamically to an existing image.
 
Does anyone have any sample code and/or pointers that might help me out?
I work best from examples, rather than muddling through the manual
(though that's what I'm doing right now.)
 
Ideally, if someone has an example of a reusable function to write text
to existing images, that would be great.
 
Thanks.
 
--kurt