The Watermark extension for Sell Media allows you to protect your large images in one click using a watermark image of your choice. You can choose to protect all large images on your site, or just those that you plan on selling using the Sell Media plugin. Simply check the “Watermark All Images” checkbox on the Settings page.
The extension doesn’t watermark the original source file (which is already protected if you’re using the Sell Media plugin).
For best results use a transparent PNG and make sure your watermark is smaller than your image (100 pixels by 100 pixels works great).
This Watermark extension does not overwrite, create new images, or harm existing images. Images must be hosted locally, not on a CDN.