Digital Light & Color

I imagine Watermark Transformation uses Blend mode? Would it be complicated to add a few others to it such as Soft Light, Hard Light, Negative, and Abs. Difference?

Added for next release.

Great, thanks! I just realized that the Blend (and now Watermark) list of blending methods is different (richer) than the Composite list. Is it by design?

Not really -- Blend was implemented later as a version of Composite with more blending modes and without alignment and an overlay mask.