Hmm, yeah, I hadn't thought that all the way through.
Thinking now though at his choice of words though, he specifically says "photo negative." I'm kind of floundering on thinking this all the way through, but a photo negative isn't a negation, but an inversion:
"A positive image is a normal image. A negative image is a total inversion, in which light areas appear dark and vice versa. A negative color image is additionally color-reversed, with red areas appearing cyan, greens appearing magenta and blues appearing yellow."
So, Earwa is our inverse word. I need to think more about this...