Hi,
Greetings.
I read the description of the project and want to do this for you.
My Idea: I'll create a PHP script that can be used from your site or from your local machine (provided php is installed). This script will read the image files from some some folder on the server/local drive and add the text to it with given font and color. If you want we can use a config file that can list all the required parameters to use on the button. I would like to talk on this in detail.
I don't have enough rating to prove my ability, so I have created a demo of this application on my server where you can select an Image on my server and type the text in the box below it and click to submit. It processes the Image and displays back to you. In you case it will save the Image back to the drive. I can provide you the link after 1 hour, once I finish this demo.
Please let me know if you are interested.
Thanks and regrds
Pankaj Avasthi