This effect mimics the look of the first frame of a roll of film that has been partially exposed to light when loaded into the camera.
Two settings control the look of the burn: filmburn set to true switches on the effect and renders an orange and red burn, or a yellow and green burn. Then, ragged_filmburn set to true will render a burn similar to torn paper, while false renders a smoother, more light leak-like burn.
The settings filmburn_min_reach and filmburn_max_reach, both given in percentages, sets the range of coverage the burn may have.
EXAMPLE ONE: filmburn set to true, ragged_filmburn set to false, filmburn_min_reach set to 10 and filmburn_max_reach set to 50 will render a burn with torn paper effect, that randomly covers between 10 and 50 percent of the frame.
EXAMPLE TWO: filmburn set to true, ragged_filmburn set to true, filmburn_min_reach set to 30 and filmburn_max_reach set to 30 will render a smooth burn, that always covers between 30 percent of the frame.
EXAMPLE THREE: filmburn set to false, ragged_filmburn set to true, filmburn_min_reach set to 10 and filmburn_max_reach set to 50 won’t render any film burn. When filmburn is set to false the rest of the settings have no effect.
The settings above are merely starting values from which the effect builds. There is so much randomness involved in constructing these burns that each script run is like pulling the arm on a slot machine. You are guaranteed to get a unique burn each time, and you may need to run Poserframes many times on an image before you get something you like.