How to make Watermark for Joomla 2.5?

Question

Joomla

Hello, I ran into a problem with the implementation of watermark on Joomla. The fact is that I have virtuemart, and when adding a product, I add a description with pictures. How to make a watermark exactly on those pictures that are in the description? Maybe there is a plugin? I must say right away that the .htaccess method is not suitable, because it doesn’t work for me no matter how hard I tried, apparently because of the hoster. Thank you in advance.