how red light camera works ?

Hi Guys

I have general question about red light camera works.

Well I've seen people crossing lights with camera system when the lights are already amber and system not doing any picture, also I've seen when people crossing on red and then picture is done, but how the system works, what to do if you approach lights with camera system and when you are close to lights they change to amber and it is impossible to safety stop. i'm not saying like you about 8-15 meters before lights and you see its amber but u press accelerator pedal to get before change to red, I'm saying when you are close to lights and then change to amber,

what's your opinion or any one has idea how this lights works.