Complete the Base, Thumbnail, Small, and Swatch Image image settings as follows. The fields in each section are the same. a. Enter the Image Opacity as a percentage. For example: 40 b. Enter the Image Size, in pixels. For example: 200 x 200 c. Tap Upload, and choose the image file that you want to use. d. Set Image Position to determine where the watermark appears.
5. When complete, tap Save Config . 6. When prompted to refresh the cache, tap the Cache Management link in the system message. Then, refresh the invalid cache.
No third party modules
The only customization is fixing bug as outlined here and in many other threads.