pub fn unsharp(amount: f32) -> Option<String>Expand description
ffmpeg’s unsharp=5:5:amount (luma only) as a PREOUTPUT hook: after scaling and the LUT, on
gamma-encoded RGB, where the CPU chain runs it. The 5x5 kernel is the separable binomial
[1 4 6 4 1]/16 blur, out = in + amount * (in - blur) on BT.601 luma (what ffmpeg’s
auto-inserted RGB -> YUV conversion uses); adding the same delta to R, G and B moves Y only.
None for amount == 0.