Getting started with OpenCV 2 4 and MinGW on Windows 7

Question

How do I install OpenCV 2 4 and compile my code with MinGW

User · Answer

If you installed opencv 2 4 2 then you need to change the -lopencv core240 to -lopencv core242  I made the same mistake

User · Answer

The instructions in  bsdnoobz answer are indeed helpful  but didn t get OpenCV to work on my system     Apparently I needed to compile the library myself in order to get it to work  and not count on the pre-built binaries  which caused my programs to crash  probably due to incompatibility with my system    I did get it to work  and wrote a comprehensive guide for compiling and installing OpenCV  and configuring Netbeans to work with it     For completeness  it is also provided below     When I first started using OpenCV  I encountered two major difficulties    Getting my programs NOT to crash immediately  Making Netbeans play nice  and especially getting timehe debugger to work    I read many tutorials and  how-to  articles  but none was really comprehensive and thorough  Eventually I succeeded in setting up the environment  and after a while of using this  great  library  I decided to write this small tutorial  which will hopefully help others   The are three parts to this tutorial    Compiling and installing OpenCV  Configuring Netbeans  An example program    The environment I use is  Windows 7  OpenCV 2 4 0  Netbeans 7 and MinGW 3 20  with compiler gcc 4 6 2    Assumptions  You already have MinGW and Netbeans installed on your system   Compiling and installing OpenCV  When downloading OpenCV  the archive actually already contains pre-built binaries  compiled libraries and DLL s  in the  build  folder  At first  I tried using those binaries  assuming somebody had already done the job of compiling for me  That didn t work   Eventually I figured I have to compile the entire library on my own system in order for it to work properly   Luckily  the compilation process is rather easy  thanks to CMake   CMake  stands for Cross-platform Make  is a tool which generates makefiles specific to your compiler and platform  We will use CMake in order to configure our building and compilation settings  generate a  makefile   and then compile the library   The steps are    Download CMake and install it  in the installation wizard choose to add CMake to the system PATH   Download the  release  version of OpenCV  Extract the archive to a directory of your choice  I will be using c  opencv   Launch CMake GUI    Browse for the source directory c  opencv   Choose where to build the binaries  I chose c  opencv release   Click  Configure   In the screen that opens choose the generator according to your compiler  In our case it s  MinGW Makefiles    Wait for everything to load  afterwards you will see this screen   Change the settings if you want  or leave the defaults  When you re done  press  Configure  again  You should see  Configuration done  at the log window  and the red background should disappear from all the cells   At this point CMake is ready to generate the makefile with which we will compile OpenCV with our compiler  Click  Generate  and wait for the makefile to be generated  When the process is finished you should see  Generating done   From this point we will no longer need CMake   Open MinGW shell  The following steps can also be done from Windows  command prompt     Enter the directory c  opencv release   Type mingw32-make and press enter  This should start the compilation process    When the compilation is done OpenCV s binaries are ready to be used  For convenience  we should add the directory C  opencv release bin to the system PATH  This will make sure our programs can find the needed DLL s to run     Configuring Netbeans  Netbeans should be told where to find the header files and the compiled libraries  which were created in the previous section    The header files are needed for two reasons  for compilation and for code completion  The compiled libraries are needed for the linking stage   Note  In order for debugging to work  the OpenCV DLL s should be available  which is why we added the directory which contains them to the system PATH  previous section  step 5 4    First  you should verify that Netbeans is configured correctly to work with MinGW  Please see the screenshot below and verify your settings are correct  considering paths changes according to your own installation   Also note that the make command should be from msys and not from Cygwin     Next  for each new project you create in Netbeans  you should define the include path  the directory which contains the header files   the libraries path and the specific libraries you intend to use   Right-click the project name in the  projects  pane  and choose  properties    Add the include path  modify the path according to your own installation      Add the libraries path     Add the specific libraries you intend to use  These libraries will be dynamically linked to your program in the linking stage  Usually you will need the core library plus any other libraries according to the specific needs of your program     That s it  you are now ready to use OpenCV   Summary  Here are the general steps you need to complete in order to install OpenCV and use it with Netbeans    Compile OpenCV with your compiler  Add the directory which contains the DLL s to your system PATH  in our case  c  opencv release bin   Add the directory which contains the header files to your project s include path  in our case  c  opencv build include   Add the directory which contains the compiled libraries to you project s libraries path  in our case  c  opencv release lib   Add the specific libraries you need to be linked with your project  for example  libopencv core240 dll a     Example -  Hello World  with OpenCV  Here is a small example program which draws the text  Hello World      on a GUI window  You can use it to check that your installation works correctly  After compiling and running the program  you should see the following window      include  opencv2 opencv hpp   include  opencv2 highgui highgui hpp   using namespace cv   int main int argc  char   argv          create a gui window      namedWindow  Output  1          initialize a 120X350 matrix of black pixels      Mat output   Mat  zeros  120  350  CV 8UC3           write text on the matrix      putText output               Hello World                  cvPoint 15 70               FONT HERSHEY PLAIN              3              cvScalar 0 255 0               4          display the image      imshow  Output   output          wait for the user to press any key      waitKey 0        return 0

User · Answer

This isn t working for me  I spent few days following every single tutorial I found on net and finally i compiled my own binaries  Everyting is described here  OpenVC 2 4 5  eclipse CDT Juno  MinGW error 0xc0000005  After many trials and errors I decided to follow this tutorial and to compile my own binaries as it seems that too many people are complaining that precompiled binaries are NOT working for them  Eclipse CDT Juno was already installed   My procedure was as follows    Download and install MinGW and add to the system PATH with c  mingw bin Download cmake from http   www cmake org and install it Download OpenCV2 4 5 Windows version Install unzip Opencv to C  OpenCV245PC   README index rst and CMakeLists txt are there with all subfolders  Run CMake GUI tool  then Choose C  OpenCV245PC  as source Choose the destination  C  OpenCV245MinGW x86  where to build the binaries Press Configure button  choose MinGW Makefiles as the generator  There are some red highlights in the window  choose options as you need   Press the Configure button again  Configuring is now done  Press the Generate button  Exit the program when the generating is done  Exit the Cmake program  Run the command line mode  cmd exe  and go to the destination  directory C  OpenCV245MinGW x86 Type  mingw32-make   You will see a progress of building  binaries  If the command is not found  you must make sure that the  system PATH is added with c  mingw bin  The build continues  according the chosen options to a completion  In Windows system PATH  My Computer   Right button click    Properties   Advanced   Environment Variables   Path  add the  destination s bin directory  C  OpenCV245MinGW x86 bin  RESTART COMPUTER Go to the Eclipse CDT IDE  create a C   program using the sample OpenCV code  You can use code from top of this topic   Go to Project   Properties   C C   Build   Settings   GCC C   Compiler   Includes  and add the source OpenCV folder  C  OpenCV245PC build include  Go to Project   Properties   C C   Build   Settings   MinGW C   Linker   Libraries  and add to the Libraries  -l  ONE BY ONE  this could vary from project to project  you can add all of them if you like or some of them just the ones that you need for your project   opencv calib3d245 opencv contrib245 opencv core245 opencv features2d245 opencv flann245 opencv gpu245 opencv highgui245 opencv imgproc245 opencv legacy245 opencv ml245 opencv nonfree245 opencv objdetect245 opencv photo245 opencv stitching245 opencv video245 opencv videostab245 Add the built OpenCV library folder    C  OpenCV245MinGW x86 lib  to Library search path  -L     You can use this code to test your setup    include  lt opencv2 core core hpp gt   include  lt opencv2 highgui highgui hpp gt   include  lt opencv2 opencv hpp gt   include  lt iostream gt   using namespace std  using namespace cv   int main      Mat img   imread  c  lenna png   CV LOAD IMAGE COLOR    namedWindow  MyWindow   CV WINDOW AUTOSIZE   imshow  MyWindow   img    waitKey 0   return 0      Don t forget to put image to the C    or wherever you might find suitable  just be sure that eclipse have read acess

User · Answer

On Windows 64bits it  s works    Download opencv-3 0  beta   MinGW  command line tool   Add above respective bin folder to PATH var  Create an folder  release   could be any name  into   Into created folder  open prompt terminal and exec the below commands  Copy and Past this command   cmake -G  MinGW Makefiles  -D CMAKE CXX COMPILER mingw32-g   exe -D WITH IPP OFF MAKE MAKE PROGRAM mingw32-make exe      Execute this command mingw32-make Execute this command mingw32-make install   DONE

User · Answer

As pointed out by  Nenad Bulatovic one has to be careful while adding libraries 19th step   one should not add any trailing spaces while adding each library line by line  otherwise mingw goes haywire

User · Answer

1  Installing OpenCV 2 4 3  First  get OpenCV 2 4 3 from sourceforge net  Its a self-file-extracting so just double click the file to start installation  Install it in a directory  say C       Wait until all files get extracted  It will create a new  directory C  opencv which contains OpenCV header files  libraries  code samples  etc   Now you need to add C  opencv build x86 mingw bin directory to your system PATH  This directory contains OpenCV DLLs which is required for running your code   Open Control Panel  rarr  System  rarr  Advanced system settings  rarr  Advanced Tab  rarr  Environment variables     You will see a window like shown below     On the System Variables section  select Path  1   click Edit     2   add C  opencv build x86 mingw bin  3  then click Ok   This will completes the OpenCV 2 4 3 installation on your computer     2  Installing MinGW compiler suite  I highly recommend you to use gcc  GNU Compiler Collection  for compiling your code  gcc is the compiler suite widely available in Linux systems and MinGW is the native port for Windows   Download the MinGW installer from Sourceforge net and double click to start installation  Just follow the wizard and select the directory to be installed  say C  MinGW     Select  C Compiler  and  C   Compiler  to be installed     The installer will download some packages from the internet so you have to wait for a while  After the installation finished  add C  MinGW bin to your system path using the steps described before     To test if your MinGW installation is success  open a command-line box and type  gcc  If everything is ok  it will display this message   gcc  fatal error  no input files compilation terminated   This completes the MinGW installation  now is the time to write your  Hello  World   program     3  Write a sample code  Open your text editor and type the code below and save the file to loadimg cpp    include  opencv2 highgui highgui hpp   include  lt iostream gt   using namespace cv  using namespace std   int main int argc  char   argv      Mat im   imread argc    2   argv 1     lena jpg   1     if  im empty            cout  lt  lt   Cannot open image    lt  lt  endl      return -1         imshow  image   im     waitKey 0      return 0      Put lena jpg or any image you like in the same directory with the file above  Open a command-line box and compile the code above by typing   g   -I C  opencv build include  -L C  opencv build x86 mingw lib  loadimg cpp -lopencv core243 -lopencv highgui243 -o loadimg   If it compiles successfully  it will create an executable named loadimg exe    Type   loadimg   To execute the program  Result       4  Where to go from here   Now that your OpenCV environment is ready  what s next    Go to the samples dir  rarr  C  opencv samples cpp  Read and compile some code  Write your own code

User · Answer

I used the instructions in this step-by-step and it worked    http   nenadbulatovic blogspot co il 2013 07 configuring-opencv-245-eclipse-cdt-juno html

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