Function ippiColorToGray_64f_C3C1R 

pub unsafe extern "C" fn ippiColorToGray_64f_C3C1R(
    pSrc: *const f64,
    srcStep: i32,
    pDst: *mut f64,
    dstStep: i32,
    roiSize: IppiSize,
    coeffs: *const f64,
) -> i32