    inline int mod(const unsigned char x, const unsigned char m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return x%m;
    }
    inline int mod(const unsigned char x, const unsigned char m) {
      if (!m) throw CImgArgumentException("cimg::mod(): Specified modulo value is 0.");
      return x%m;
    }