opencv2 compatibility

[smihael]

This should maybe be added as an extra branch to enable compiling on Ubuntu 16.04 (see #1 and #2)

[derzu]

Hi Smihael,

I think the problem is the OpenCV version, the versions above 3.0 works with the include:
opencv2/<module>.hpp
The versions below 3.0 uses:
opencv2/<module>/<module>.hpp

Look at these links:
https://docs.opencv.org/3.2.0/db/dfa/tutorial_transition_guide.html
https://stackoverflow.com/a/43701862/1178478

With OpenCV version are you using?

[smihael]

Exactly, the problem is that in Ubuntu 16.04 repositories only OpenCV2 2.x is available. There is no need to require OpenCV 3.x as the code compiles and runs fine with OpenCV 2.x.

[derzu]

I think we can check the OpenCV version on the compilation time.

Look at this link:
https://stackoverflow.com/questions/2422514/how-to-check-for-opencv-on-ubuntu-9-10

So we can do a marco #if like that:

#if CV_VERSION >= 3
#include <opencv2/core.hpp>
#else
#include <opencv2/core/core.hpp>
#endif

I do not tested this code, but I think it works.