Function assigned_boundary_density 

pub fn assigned_boundary_density(
    img: &CaptureImage,
    eps: u8,
    figure_cut: f32,
) -> f32

boundary_density against the reference figure_ground_ratio assigns — NO_GROUND at or above figure_cut, where the modal band is the figure, and modal_ground below it (ADR-0200).

This is the flatness conjunction’s second term. The statistic is unchanged and so is everything ADR-0130 established about it; what the role classifier supplies is the reference, which is the half ADR-0161 found wrong. Pointed at a blot’s mass it reads the 2/r perimeter of a solid disc; pointed at a print’s ink it reads the ink’s perimeter rather than the paper’s perforation.

figure_cut is a measurement the caller owns, and so is any floor compared against the value returned. A cut is a bound over a population — the lowest blot against the highest non-blot among the frames a first term can reach — and there is no value defensible outside the population it was read from.

The two halves have different resolution bindings, which is the trap. The ratio is areal and near size-invariant; the density is perimeter over area and goes as ~1/L in the capture’s linear size, so a floor on it halves with a doubling of the capture. A caller reading at another size re-derives its floor from its own anchors and does not scale one in (ADR-0071).