Function im_dif_std 

pub unsafe extern "C" fn im_dif_std(
    im: *mut VipsImage,
    xpos: c_int,
    ypos: c_int,
    xsize: c_int,
    ysize: c_int,
    dx: c_int,
    dy: c_int,
    pmean: *mut f64,
    pstd: *mut f64,
) -> c_int