It would be interesting to see if you could use a system like this to automagically derive background colors for image display, picking muted complimentary colors to make the dominant color in an image "pop", so to speak.
You can do this by representing the colors into HSV and then modifying the hue by 180%, desaturating them and then adjusting the brightness (v). Most color libraries will let you deal in RGB(A) or HSV so this is pretty straightforward to DIY.