Running OpenCV 3 in Mac Terminal

Question

For the past week, I have been trying to run some simple OpenCV programs using the terminal. I have tried many tutorials and recommendations from various forums with little

Answer 1

You haven't specified:

1. the include path (header search path) using -I"/path/to/your/include"
2. the path to the libraries using -L"/path/to/libraries"
3. which libraries to link against, in this case core and highgui: -lopencv_core -lopencv_highgui

I have opencv headers in /opt/local/include and libraries in /opt/local/lib, so to compile a basic program like this:

#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

int main( int argc, char** argv )
{
        Mat src = Mat(Size(320,240),CV_64F);;
        namedWindow("test");

        cout << "press any key to close" << endl;

        while(true){
                randn(src,0,1.0);
                imshow("test",src);
                if(waitKey() > 0) break;
        }
}

I compiled like so:

g++ main.cpp -I"/opt/local/include/" -L"/opt/local/lib/" -lopencv_core -lopencv_highgui -o main

Then ran ./main:

Bare in mind you might have opencv installed in the /usr/local folder not /opt/local depending how you compiled/installed OpenCV.

Also, you might have pkg-config installed which can come in handy when you need to link against more libraries.

For example, you can run:

pkg-config --libs --cflags opencv

which in my case outputs:

-I/opt/local/include/opencv -I/opt/local/include -L/opt/local/lib -lopencv_calib3d -lopencv_contrib -lopencv_core -lopencv_features2d -lopencv_flann -lopencv_gpu -lopencv_highgui -lopencv_imgproc -lopencv_legacy -lopencv_ml -lopencv_nonfree -lopencv_objdetect -lopencv_photo -lopencv_stitching -lopencv_superres -lopencv_ts -lopencv_video -lopencv_videostab 

but in your case, it should output your particular OpenCV paths.

This would simplify compiling to this:

g++ main.cpp `pkg-config --libs --cflags opencv` -o main

The guide you linked to uses cmake which generates Makefiles for you. That's another nice options. Also, based on the same guide, you should have XCode installed which you can use to create a Command Line Tool and point the Header Search Paths and Library Search Paths.

Answer 2

I create a similar file that maybe can help you.

First I use:

sudo brew install opencv

Then I install the opencv.3.0 according to the hint given by the terminal. Then in the .cpp file which needs the API from opencv, I use:

#include "opencv2/opencv.hpp"

As my only include file about opencv. Actually, at that project I use highgui, core, and imgprog. But no worries here, I will show you how to solve them in linking part.

After you finish your project, you are going to compile your project on the terminal.

Because I also used the JNI interface, so I still need to link the jni.h.

Here we go:

g++   xxxx.cpp xxx.cpp -lstdc++ -fPIC -shared (to create a shared object)  
-I/absolute path/ (we can use -I  to be followed with  the absolute path of the library you need to use )
-I/Users/yuanzhan/Downloads/OpenCV-2.0.0/src/
-I /Users/yuanzhan/Downloads/OpenCV-2.0.0/include/opencv/ -I/usr/local/Cellar/opencv3/3.1.0_3/lib   -lopencv_core (open the library for use if you use the API fro here)-lopencv_highgui -lopencv_imgproc -L.(i put the cv2. on local otherwise you can add the absolute path here) -lcv2(use the package)  -v -o libopenCvSDK.so(generate my .so package).