Function sixel_helper_normalize_pixelformat 

pub unsafe extern "C" fn sixel_helper_normalize_pixelformat(
    dst: *mut c_uchar,
    dst_pixelformat: *mut PixelFormat,
    src: *const c_uchar,
    src_pixelformat: PixelFormat,
    width: c_int,
    height: c_int,
) -> Status