radius:this fraction of the image width will be the blur radius
epsilon:the edge weight for the guided filter
gamma:the gamma correction to apply before quantisation to zones. lower this value if you need more zones in the blacks, increase it for finer resolution in the highlights. this can be a great way to separate the image exactly where you need it.
nzones:the number of zones the image should be quantised into
zone:the exposure compensation values for the zones from dark to bright.
