nP0 – center of the image,
nRadius Ri picked by analyzing histogram: it should
include both pixels from pupil and surrounding areas to ensure
that next Pi differs from previous,
nStep: ΔPi = l(Pi+1 -Pi ) with l in the range [0,2] with >1 values speeding up
convergence at risk of
“overshooting”.
nNext center approximation: Ci+1 = Pi + ΔPi