Since there are two different filters, I could calibrate the result and figure out what color it is to match the table below. Of course we could do no useful work with the camera system, just measure the relative humidity. I have modified two cameras to have gas in and out fittings. Hard to keep metal scraps out of the works. No, I have not yet made this mistake.
Nothing is ever easy.
The only one I can find is white plastic. I would like to sense the relative humidity. With the two, I think one can compute the dew point.