[prewett]

I think they usually have a black and white camera with filters of specific wavelengths, some of which roughly correspond to red, green, blue, and they combine them. The color pictures I've seen from Mars and Cassini usually say "approximate true color."

[Freaky]

They have no green (495-570nm) filter, just panchromatic (400-975nm), blue (400-550nm), red (540-700nm), near-IR (780-975nm) and narrow-band methane (860-910nm).