Function signal_gated_erosion 

pub fn signal_gated_erosion(
    mask: &[u8],
    magnitude: &[f64],
    grid: &Grid,
    params: &SignalErosionParams,
) -> Vec<u8> 

Erode mask only where the signal is low (see the module docs).

magnitude should be a combined magnitude (e.g. the root-sum-of-squares over echoes) on the same grid. Returns the refined mask (0/1).