Function ippiGradientColorToGray_32f_C3C1R 

pub unsafe extern "C" fn ippiGradientColorToGray_32f_C3C1R(
    pSrc: *const f32,
    srcStep: i32,
    pDst: *mut f32,
    dstStep: i32,
    roiSize: IppiSize,
    norm: u32,
) -> i32