I put in a temporary fix for my purposes by injecting a JavaScript that, onload; analyzes the color value (lightness or darkness) of my site header's background-color and switches out the footer "logo" I uploaded in lieu of an "icon," according to the same color value. This allows me to change from Protean Light Mix or any other mix I create with light headers to dark header and footers and still have the logo uploaded to the footer stand out. I say "temporary fix," because it is based on layout ids or classes designed into the Protean template system as markers to determine header and footer. That means the fix is more fragile than I would like. Still, it does work seamlessly.