Watermark image will let you superimpose an image on top of another image. Commonly the image being superimposed has a transparent background. Similar to classical watermarks in paper, this procedure will enable authenticating the source of a resource or prevent others from using your legally copyrighted work.

The watermark image will get scaled and centered onto the resource it is being superimposed on. The rational for this is that putting it near the edges would make it too easy to crop off. However this approach therefore may require some tinkering with the watermark image until you have something that is clear but not too intrusive so as to not disrupt the usability/viewability of the resource.

The watermarked resource is presented inline for download. The image will only stay available there for a limited time. An automated process will remove it usually within an hour. So it is advisable to re-download it immediately.