Function box_segment 

fn box_segment(
    image: &[f64],
    mask: &[u8],
    nbox: usize,
    nx: usize,
    ny: usize,
    nz: usize,
) -> Vec<u8> 

Box segmentation for finding tissue regions

Divides the image into nbox^3 boxes and identifies voxels that consistently appear in the high-intensity range across multiple boxes.