Image block
Using the standard image block, I don’t see a real way to add a watermark. You can tint it, add text overtop and an image… but you can’t control where the image appears nor its transparency. I don’t think any of this is useful for creating a watermark (and doesn’t stop someone from right-clicking to get the location of the image to download anyway).
Text can be added
Next Gen Gallery
I don’t see any kind of watermarking or overlay option here.
