Some people might prefer GD to Image::Magick for its speed and lack of bloat. Also it will install with only one, or all, of the image libraries you choose.
You could do what you want with GD and the GD::string() function...

## extracted and simplified from a bit of working code I have
my $fname = "/path/to/your/file.jpg";
my $text = "What you want to say.";

open (IMG, "<$fname") or die;
my $size = -s $fname;
my $data; 
read IMG, $data, $size;
close IMG;
die "blah" unless $data;

use GD;
# my $itype = image_type(getType_bymagic($data));
# die unless $itype eq "Jpeg";
# my $method = "newFrom${itype}Data";
my $method = "newFromJpegData";
my $i = GD::Image->$method($data, 1);
my $fg = $i->colorAllocate(102,102,102);

$i->string(gdMediumBoldFont,7,7,$text,$fg);
return \$i->png;
[download]

...however, you would then be left with managing the centering and wrapping of text yourself.
For that reason I would recommend looking into the GD::Text, GD::Text::Align, and GD::Text::Wrap modules.

Good luck.
-xtype