A filter on the lens designed to pass the paint wavelengths is another alternative. Painted objects would produce a higher signal that the surrounding environme

A filter on the lens designed to pass the paint wavelengths is another alternative. Painted objects would produce a higher signal that the surrounding environment. But I'm not sure how well this would play with the light changes. Some nit-pick. TV cameras usually used Philips prism. Dichroic mirrors were (and still are) more common on projectors.