######
##
## Corona Edge Mask by mf
##
## Finds edges by creating coronas in the picture.
##
## Works only on Y.
##


function CoronaEdgeMask(clip input) {

input.Inflate().Inflate().Inflate().Inflate()
inflated = last

YV12Subtract(input, inflated).Greyscale()
dsubtracted = last

Overlay(dsubtracted, dsubtracted, mode="exclusion")
dinvertfix = last

Overlay(dinvertfix, dinvertfix, mode="darken")
Levels(0, 1.0, 127, 255, 0)
dmask = last

input.Deflate().Deflate().Deflate().Deflate()
deflated = last

YV12Subtract(deflated, input).Greyscale()
lsubtracted = last

Overlay(lsubtracted, lsubtracted, mode="exclusion")
linvertfix = last

Overlay(linvertfix, linvertfix, mode="darken")
Levels(0, 1.0, 127, 255, 0)
lmask = last

Overlay(dmask, lmask, mode="lighten").Greyscale()

}