How to generate an image when accessing it?

Question

PHP

Hello.
There is a forum with the ability to insert images into a post. I insert a dummy image link that leads to my hosting. When posting a message, the tag appears on the forum page . When loading the page of a forum thread, a request for a picture will go to my server. How can I intercept this call to generate a picture? Purpose: the picture should change depending on the content of the forum thread. I hope the end idea is clear. PS I'm afraid of traffic, maybe you can do something better. <img src="http://myhosting.ru/img.png">

Answer 1

as an option - a redirect in the .htaccess file to the script