Use the luminance, but not the chroma values, of a portrait of a face to modulate the brightness of a watercolour painting of a still-life. Didn't get quite what I was looking for, but still looks good.
Use the luminance, but not the chroma values, of a portrait of a face to modulate the brightness of a watercolour painting of a still-life, to create the illusion of a face in the painting.