Function im_similarity_area 

pub unsafe extern "C" fn im_similarity_area(
    in_: *mut VipsImage,
    out: *mut VipsImage,
    a: f64,
    b: f64,
    dx: f64,
    dy: f64,
    ox: c_int,
    oy: c_int,
    ow: c_int,
    oh: c_int,
) -> c_int