// 'range': a minimum and maximum radius.
// 'scale': <= 1.0, to speed up the process.
let findRadius (img: Image<Gray, 'TDepth>) (range: int * int) (scale: float) : int =
// 'range': a minimum and maximum radius.
// 'scale': <= 1.0, to speed up the process.
let findRadius (img: Image<Gray, 'TDepth>) (range: int * int) (scale: float) : int =