Hi all,

I am creating a bunch of function for channel merging, thus I was looking in channel_algorithm.hpp and I saw something that may slow down processes...
I don't know if I'm right, but on line 362:

/// \ingroup ChannelConvertAlgorithm
/// \brief Converting from one channel type to another.
template <typename DstChannel, typename SrcChannel> // Model ChannelConcept (could be channel references)
inline typename channel_traits<DstChannel>::value_type channel_convert(SrcChannel src) {
return channel_converter<typename channel_traits<SrcChannel>::value_type,
typename channel_traits<DstChannel>::value_type>()(src);
}

There is no reference on parameter src.
That not a very good idea because references aren't hold by templates function (even if inlined). This may invoke copy constructor and can slow down the processes a "lot"...

Here is an example that shows I'm right in theory:

// "Slow" on big objects
template<typename P>
inline void testPtr1(P a) {
    std::cout << "In called function inequality ptr of a: " << (int)&a << std::endl;
}

// Better
template<typename P>
inline void testPtr2(P &a) {
    std::cout << "In called function equality ptr of a: " << (int)&a << std::endl;
}

template<typename P>
void test(const P & a) {
    std::cout << "Base ptr of a: " << (int)&a << std::endl;
    testPtr1(a);
}

int main() {
    int a = 0;
    test(a);
    return 0;
}