Function susceptibility_mask 

pub fn susceptibility_mask(
    chi_ppm: &[f64],
    threshold_ppm: f64,
    contrast: SmwiContrast,
) -> Vec<f64>

Build the SMWI weighting mask from a susceptibility map

paramagnetic: w(χ) = clamp(1 - χ/t, 0, 1)
diamagnetic:  w(χ) = clamp(1 + χ/t, 0, 1)

Non-finite susceptibilities map to 0 so they cannot propagate into the weighted image or a later mIP.

Arguments

• chi_ppm - Susceptibility map in ppm
• threshold_ppm - Susceptibility threshold in ppm (non-positive → 1 ppm)
• contrast - Which sources to suppress

Returns

Weighting mask with values in [0, 1]