Function pred_directional

pub(crate) fn pred_directional<T: Pixel>(
    output: &mut PlaneRegionMut<'_, T>,
    above: &[T],
    left: &[T],
    top_left: &[T],
    p_angle: usize,
    width: usize,
    height: usize,
    bit_depth: usize,
    ief_params: Option<IntraEdgeFilterParameters>,
)