Package opencv was not found in the pkg-config search path

I have installed OpenCV using the instructions in https://help.ubuntu.com/community/OpenCV

$ sudo su
$ sudo apt-get install build-essential
$ sudo apt-get install libavformat-dev
$ sudo apt-get install ffmpeg
$ sudo apt-get install libcv2.3 libcvaux2.3 libhighgui2.3 python-opencv opencv-doc libcv-dev libcvaux-dev libhighgui-dev

now when i execute "pkg-config --cflags --libs opencv" i get this error:

Package opencv was not found in the pkg-config search path.
Perhaps you should add the directory containing `opencv.pc'
to the PKG_CONFIG_PATH environment variable
No package 'opencv' found

how can I resolve this problem?

-------UPDATE-------

OK, I figured out how to solve the problem...

I made a file named "opencv.pc" and copied it to "/usr/local/lib/pkgconfig" Then i added these two lines to ".bashrc":

PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig
export PKG_CONFIG_PATH

that's it! everything is OK now.

the contents of the file are:

prefix=/usr
exec_prefix=${prefix}
includedir=${prefix}/include
libdir=${exec_prefix}/lib

Name: opencv
Description: The opencv library
Version: 2.x.x
Cflags: -I${includedir}/opencv -I${includedir}/opencv2
Libs: -L${libdir} -lopencv_calib3d -lopencv_imgproc -lopencv_contrib -lopencv_legacy -lopencv_core -lopencv_ml -lopencv_features2d -lopencv_objdetect -lopencv_flann -lopencv_video -lopencv_highgui

UPDATE - 2014

it seems that the ubuntu community has completed the documentation on installing openCV, all you have to do now is to download the installation script from https://github.com/jayrambhia/Install-OpenCV/blob/master/Ubuntu/opencv_latest.sh and execute it.

From your question I guess you are using Ubuntu (or a derivate). If you use:

apt-file search opencv.pc

then you see that you have to install libopencv-dev.

After you do so, pkg-config --cflags opencv and pkg-config --libs opencv should work as expected.

with opencv 4.0;

• add -DOPENCV_GENERATE_PKGCONFIG=ON to build arguments
• pkg-config --cflags --libs opencv4 instead of opencv

it seems that the ubuntu community has completed the documentation on installing openCV,

so all you have to do now is to download the installation script from here and execute it.

don't forget to make it executable:

chmod +x opencv_latest.sh

then

./opencv_latest.sh

When you run cmake add the additional parameter -D OPENCV_GENERATE_PKGCONFIG=YES (this will generate opencv.pc file)

Then make and sudo make install as before.

Use the name opencv4 instead of just opencv Eg:-

pkg-config --modversion opencv4

I installed opencv following the steps on https://docs.opencv.org/trunk/d7/d9f/tutorial_linux_install.html

Except on Step 2, use: cmake -D CMAKE_BUILD_TYPE=Release -D OPENCV_GENERATE_PKGCONFIG=YES -D CMAKE_INSTALL_PREFIX=/path/to/opencv/ ..

Then locate the opencv4.pc file, mine was in opencv/build/unix-install/

Now run: $ export PKG_CONFIG_PATH=/path/to/the/file

Hi first of all i would like you to use 'Synaptic Package Manager'. You just need to goto the ubuntu software center and search for synaptic package manager.. The beauty of this is that all the packages you need are easily available here. Second it will automatically configures all your paths. Now install this then search for opencv packages over there if you found the package with the green box then its installed but else the package is not in the right place so you need to reinstall it but from package manager this time. If installed then you can do this only, you just need to fill the OpenCV_DIR variable with the path of opencv (containing the OpenCVConfig.cmake file)

    export OpenCV_DIR=<path_of_opencv>

I got the same error when trying to compile a Go package on Debian 9.8:

# pkg-config --cflags  -- libssl libcrypto
Package libssl was not found in the pkg-config search path.
Perhaps you should add the directory containing `libssl.pc'

The thing is that pkg-config searches for package meta-information in .pc files. Such files come from the dev package. So, even though I had libssl installed, I still got the error. It was resolved by running:

sudo apt-get install libssl-dev

$ ./configure --enable-libopencv
ERROR: opencv not found using pkg-config


$ cat /usr/lib64/pkgconfig/opencv.pc
# Package Information for pkg-config

prefix=/usr
exec_prefix=${prefix}
libdir=${exec_prefix}/lib64
includedir_old=${prefix}/include/opencv
includedir_new=${prefix}/include

Name: OpenCV
Description: Open Source Computer Vision Library
Version: 3.1.0
Libs: -L${exec_prefix}/lib64 -lopencv_shape -lopencv_stitching -lopencv_superres -lopencv_videostab -lopencv_aruco -lopencv_bgsegm -lopencv_bioinspired -lopencv_ccalib -lopencv_cvv -lopencv_dnn -lopencv_dpm -lopencv_fuzzy -lopencv_hdf -lopencv_line_descriptor -lopencv_optflow -lopencv_plot -lopencv_reg -lopencv_saliency -lopencv_stereo -lopencv_structured_light -lopencv_rgbd -lopencv_surface_matching -lopencv_tracking -lopencv_datasets -lopencv_text -lopencv_face -lopencv_video -lopencv_ximgproc -lopencv_calib3d -lopencv_features2d -lopencv_flann -lopencv_xobjdetect -lopencv_objdetect -lopencv_ml -lopencv_xphoto -lopencv_highgui -lopencv_videoio -lopencv_imgcodecs -lopencv_photo -lopencv_imgproc -lopencv_core
Libs.private: -L/usr/lib64 -lQt5Test -lQt5Concurrent -lQt5OpenGL -L/lib64 -lwebp -lpng -ltiff -ljasper -ljpeg -lImath -lIlmImf -lIex -lHalf -lIlmThread -lgdal -lgstvideo-1.0 -lgstapp-1.0 -lgstbase-1.0 -lgstriff-1.0 -lgstpbutils-1.0 -lgstreamer-1.0 -lucil -lunicap -lpangoft2-1.0 -lpango-1.0 -lgobject-2.0 -lfontconfig -lfreetype -lglib-2.0 -ldc1394 -lv4l1 -lv4l2 -lgphoto2 -lgphoto2_port -lexif -lQt5Core -lQt5Gui -lQt5Widgets -lhdf5_hl -lhdf5 -lz -ldl -lm -ltesseract -llept -lpthread -lrt -lGLU -lGL
Cflags: -I${includedir_old} -I${includedir_new}


$ pkg-config --cflags --libs opencv
-I/usr/include/opencv -lopencv_shape -lopencv_stitching -lopencv_superres -lopencv_videostab -lopencv_aruco -lopencv_bgsegm -lopencv_bioinspired -lopencv_ccalib -lopencv_cvv -lopencv_dnn -lopencv_dpm -lopencv_fuzzy -lopencv_hdf -lopencv_line_descriptor -lopencv_optflow -lopencv_plot -lopencv_reg -lopencv_saliency -lopencv_stereo -lopencv_structured_light -lopencv_rgbd -lopencv_surface_matching -lopencv_tracking -lopencv_datasets -lopencv_text -lopencv_face -lopencv_video -lopencv_ximgproc -lopencv_calib3d -lopencv_features2d -lopencv_flann -lopencv_xobjdetect -lopencv_objdetect -lopencv_ml -lopencv_xphoto -lopencv_highgui -lopencv_videoio -lopencv_imgcodecs -lopencv_photo -lopencv_imgproc -lopencv_core


$ uname -a
Linux fedora-23-x64 4.8.13-100.fc23.x86_64 #1 SMP Fri Dec 9 14:51:40 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

$ apt-file search opencv.pc $ ls /usr/local/lib/pkgconfig/ $ sudo cp /usr/local/lib/pkgconfig/opencv4.pc /usr/lib/x86_64-linux-gnu/pkgconfig/opencv.pc $ pkg-config --modversion opencv

Writing this answer specially for MacOS users.

First to install opencv use:

brew install opencv 
or brew install opencv@x (x = 2,4)  

We need to have the path of opencv.pc in the PKG_CONFIG_PATH to avoid this error. When you install opencv with brew it says something like this on console

 For pkg-config to find opencv@2 you may need to set:
  export PKG_CONFIG_PATH="/opt/homebrew/opt/opencv@2/lib/pkgconfig"

As the error suggest the reason is that opencv is not in the PKG_CONFIG_PATH variable. First check what is inside the variable using:

echo $PKG_CONFIG_PATH

To include the location of opencv.pc to the PKG_CONFIG_PATH use this

  echo 'export PKG_CONFIG_PATH="/opt/homebrew/opt/opencv/lib/pkgconfig:$PKG_CONFIG_PATH"' >> ~/.zshrc