Actually i guess what i'm looking for is alpha compositing, where in my particular use case I would use the input image as an alpha mask applied to a flat color
A common thing I find myself resorting to Photoshop for is taking a greyscale illustration, and converting it from black-on-white to black-on-transparent, allowing it to be composited on other things without resorting to blending modes. Is there a way to do this in Ronin?