_freeu  < source > ( s1: float s2: float b1: float b2: float  )   Parameters   s1 (float) —
Scaling factor for stage 1 to attenuate the contributions of the skip features. This is done to
mitigate “oversmoothing effect” in the enhanced denoising process.   s2 (float) —
Scaling factor for stage 2 to attenuate the contributions of the skip features. This is done to
mitigate “oversmoothing effect” in the enhanced denoising process.   b1 (float) — 