Function morphology_rect_u8_into 

pub fn morphology_rect_u8_into(
    input: ImageView<'_, u8, 1>,
    operation: MorphologyOperation,
    element: &StructuringElement,
    iterations: usize,
    border: BorderMode<u8, 1>,
    output: &mut [u8],
    workspace: &mut RectMorphologyWorkspace,
) -> VisionResult<()>

Applies composite rectangular morphology into caller-owned packed output.

output must contain exactly input.width() * input.height() elements. Safe Rust borrowing requires input and output storage not to overlap.