Swapping composite FG & BG colors - Is there a way to do this in hardware?

[UNIXcoffee928]

The Bit-3 Fullview 80 column card for the Atari 800 displays black text on a white background when hooked up (via composite) to an Amiga color monitor. This output is ok if you have a monochrome monitor, but is annoying on a color monitor, because of the glaring white background. Is there a way to put a device inline between the cables going to the computer & the monitor that can swap or change the colors on a composite signal? If it was RGB it would be one thing, but I don't know much about how composite signals work, and if this is possible, so I thought that I'd ask.

 

An ideal design would be something that would output Green characters on a black background, when using a color monitor, achieved by putting some kind of black box between the Composite cables going from the Atari's output and the Monitor's input, but even white characters on a black background would be better than the standard default output of the card. Maybe there is something that lets you run a composite signal into an RGB cable, and then the wires could be swapped to achieve some kind of color variation. Any ideas?