Green filters reflect green

 

Teaching about a green filter, I would say that white light hits the filter, red and blue are absorbed and green is transmitted through but it must also be true that the green reflects as well. In the case of the guide light for Silloth harbour, it is the case that some green light will be transmitted and then reflected back through the filter by the shiny light casing I could see inside, but it was mostly looking green to me because green light was reflecting from the outside of the filer back towards me without being transmitted. This will be why filters make the world seem darker because not only is part of the light absorbed but also part of the transmitted colour is actually reflected without going through, reducing the possible transmitted intensity.