前言：
2017.11.18：根据实践过程整理出第一版。
2018.01.05：更新对 pkgconfig 的说明。
----
今天在跑一个faster-rcnn的案例（https://pjreddie.com/darknet/yolo/）涉及到编译 openCV，于是又再一次编译并配置一次 OpenCV。OpenCV的编译过程需要一点时间，重要的是在编译的时候会出现一些常见的问题。整理下来有助于以后的再次使用。
值得一提的是，如果你只是使用一些深度学习框架（如，tensorflow 或者 keras 等）需要用到 opencv 的话（import cv2），只需要直接安装 opencv-python 即可。安装命令如下所示：
pip install opencv-pythonubuntu 系统下更多软件的安装和配置请参考：http://blog.csdn.net/houchaoqun_xmu/article/details/72461592
使用 ubuntu 的同志们请注意，很多情况要区分你输入的命令有没有加 “sudo”。比如说，你在安装 anaconda2 的过程中都是在“未使用sudo”的前提下进行安装（bash Anaconda2-4.3.1-Linux-x86_64.sh），此时系统中有两个python2环境。第一个是 ubuntu 系统自带的python2.7，你可以使用 sudo python 进入命令行模式；还有一个就是你刚刚安装的 Anaconda 中的 python，你可以直接键入命令 “python” 就可以直接进入命令行模式。
关键来了，如果你现在需要安装 tensorflow，你想使用 pip 命令直接安装。那么，你使用 " pip install -I tensorflow==0.12.1 " 和 “ sudo pip install -I tensorflow==0.12.1” 是完全不一样的， 它们分别使用了Anaconda和ubuntu系统自带的pip。其中，Anaconda 中集成了很多python相关的工具包，而系统自带的是没有的。在后续的使用中，要千万区分好是否使用 sudo。
参考网址：
opencv 对应的 github 地址：https://github.com/opencv/opencv/tree/3.3.0
OpenCV在Ubuntu下的安装：http://www.linuxidc.com/Linux/2016-07/132879.htm
Ubuntu16.04下安装OpenCV3.2.0：https://www.cnblogs.com/arkenstone/p/6490017.html
安装步骤：
part1：所需的相关插件、工具包
sudo apt-get install build-essential # 搭建C/C++编译环境sudo apt-get install cmake git libgtk2.0-dev pkg-config libavcodec-dev libavformat-dev libswscale-dev # 关联库sudo apt-get install python-dev python-numpy libtbb2 libtbb-dev libjpeg-dev libpng-dev libtiff-dev libjasper-dev libdc1394-22-dev # 关联库
part2：OpenCV 安装
1）到 github 下载 OpenCV 源码：
git clone https://github.com/opencv/opencv.git2）在根目录下创建一个新目录（mkdir my_build_dir），目的是存放 cmake 生成的文件
3）执行如下命令进行 cmake（注意根据实际情况修改命令中相应的路径）
cmake .. -DCMAKE_BUILD_TYPE=my_build_dir -DCMAKE_INSTALL_PREFIX=/home/hcq/document/opencv
如果遇到如下问题，请先将根目录下的 “CMakeCache.txt” 文件删掉，再重新执行一遍上述命令。
hcq@hcq-home:~/document/opencv$ cmake .
CMake Error at CMakeLists.txt:11 (message):
FATAL: In-source builds are not allowed.
You should create a separate directory for build files.
-- Configuring incomplete, errors occurred!cmake 成功后，提示如下所示：
hcq@hcq-home:~/document/opencv/my_build_dir$ cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=/home/hcq/document/opencv
-- The CXX compiler identification is GNU 5.4.0
-- The C compiler identification is GNU 5.4.0
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Performing Test HAVE_CXX11 (check file: cmake/checks/cxx11.cpp)
-- Performing Test HAVE_CXX11 - Failed
-- Found PythonInterp: /usr/bin/python2.7 (found suitable version "2.7.12", minimum required is "2.7")
-- Found PythonLibs: /usr/lib/x86_64-linux-gnu/libpython2.7.so (found suitable exact version "2.7.12")
Traceback (most recent call last):
File "<string>", line 1, in <module>
ImportError: No module named numpy.distutils
-- Found PythonInterp: /home/hcq/anaconda3/bin/python3 (found suitable version "3.6.3", minimum required is "3.4")
-- Could NOT find PythonLibs (missing: PYTHON_LIBRARIES PYTHON_INCLUDE_DIRS) (Required is exact version "3.6.3")
-- Looking for ccache - not found
-- Performing Test HAVE_CXX_FSIGNED_CHAR
-- Performing Test HAVE_CXX_FSIGNED_CHAR - Success
... ... ... （此处省略一大部分提示信息）
-- Python 2:
-- Interpreter: /usr/bin/python2.7 (ver 2.7.12)
--
-- Python 3:
-- Interpreter: /home/hcq/anaconda3/bin/python3 (ver 3.6.3)
--
-- Python (for build): /usr/bin/python2.7
-- Pylint: /home/hcq/anaconda3/bin/pylint (ver: 1.7.4, checks: 111)
--
-- Java:
-- ant: NO
-- JNI: NO
-- Java wrappers: NO
-- Java tests: NO
--
-- Matlab: Matlab not found or implicitly disabled
--
-- Documentation:
-- Doxygen: NO
--
-- Tests and samples:
-- Tests: YES
-- Performance tests: YES
-- C/C++ Examples: NO
--
-- Install path: /home/hcq/document/opencv
--
-- cvconfig.h is in: /home/hcq/document/opencv/my_build_dir
-- -----------------------------------------------------------------
--
-- Configuring done
-- Generating done
-- Build files have been written to: /home/hcq/document/opencv/my_build_dirhcq@hcq-home:~/document/opencv/my_build_dir$ ll
total 1144
drwxrwxr-x 15 hcq hcq 4096 11月 17 20:42 ./
drwxrwxr-x 16 hcq hcq 4096 11月 17 20:31 ../
drwxrwxr-x 7 hcq hcq 4096 11月 17 20:42 3rdparty/
drwxrwxr-x 9 hcq hcq 4096 11月 17 20:42 apps/
drwxrwxr-x 2 hcq hcq 4096 11月 17 20:42 bin/
-rw-rw-r-- 1 hcq hcq 349266 11月 17 20:42 CMakeCache.txt
-rw-rw-r-- 1 hcq hcq 1942 11月 17 20:42 CMakeConfig-CUDA_CONFIGCMAKE.cmake
-rw-rw-r-- 1 hcq hcq 41567 11月 17 20:41 CMakeDownloadLog.txt
drwxrwxr-x 13 hcq hcq 4096 11月 17 20:42 CMakeFiles/
-rw-rw-r-- 1 hcq hcq 4771 11月 17 20:42 cmake_install.cmake
-rw-rw-r-- 1 hcq hcq 1174 11月 17 20:41 cmake_uninstall.cmake
-rw-rw-r-- 1 hcq hcq 387001 11月 17 20:42 CMakeVars.txt
-rw-r--r-- 1 hcq hcq 11643 11月 17 20:42 CPackConfig.cmake
-rw-r--r-- 1 hcq hcq 11983 11月 17 20:42 CPackSourceConfig.cmake
-rw-rw-r-- 1 hcq hcq 431 11月 17 20:42 CTestTestfile.cmake
-rw-rw-r-- 1 hcq hcq 70 11月 17 20:41 custom_hal.hpp
-rw-rw-r-- 1 hcq hcq 5171 11月 17 20:42 cvconfig.h
-rw-rw-r-- 1 hcq hcq 582 11月 17 20:42 cv_cpu_config.h
drwxrwxr-x 3 hcq hcq 4096 11月 17 20:42 data/
drwxrwxr-x 3 hcq hcq 4096 11月 17 20:42 doc/
drwxrwxr-x 3 hcq hcq 4096 11月 17 20:42 include/
drwxrwxr-x 2 hcq hcq 4096 11月 17 20:31 junk/
drwxrwxr-x 2 hcq hcq 4096 11月 17 20:42 lib/
-rw-rw-r-- 1 hcq hcq 163514 11月 17 20:42 Makefile
drwxrwxr-x 38 hcq hcq 4096 11月 17 20:42 modules/
drwxrwxr-x 2 hcq hcq 4096 11月 17 20:42 opencv2/
-rw-rw-r-- 1 hcq hcq 14588 11月 17 20:42 OpenCVConfig.cmake
-rw-rw-r-- 1 hcq hcq 418 11月 17 20:42 OpenCVConfig-version.cmake
-rw-rw-r-- 1 hcq hcq 4303 11月 17 20:42 OpenCVGenPkgConfig.info.cmake
-rw-rw-r-- 1 hcq hcq 20232 11月 17 20:42 OpenCVModules.cmake
-rw-rw-r-- 1 hcq hcq 122 11月 17 20:41 opencv_tests_config.hpp
-rw-rw-r-- 1 hcq hcq 28238 11月 17 20:42 pylint.cmake
-rw-rw-r-- 1 hcq hcq 572 11月 17 20:18 pylintrc
drwxrwxr-x 5 hcq hcq 4096 11月 17 20:41 test-reports/
drwxrwxr-x 2 hcq hcq 4096 11月 17 20:42 unix-install/
-rw-rw-r-- 1 hcq hcq 8216 11月 17 20:42 version_string.tmpmake -j8 # 本人的PC上有8个线程sudo make -j8 install-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_frontalface_alt_tree.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_frontalface_default.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_licence_plate_rus_16stages.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_lefteye_2splits.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_frontalcatface.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_eye.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_righteye_2splits.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_eye_tree_eyeglasses.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_russian_plate_number.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_frontalcatface_extended.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_smile.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_upperbody.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_frontalface_alt2.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_profileface.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_fullbody.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/haarcascades/haarcascade_frontalface_alt.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/lbpcascades/lbpcascade_profileface.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/lbpcascades/lbpcascade_silverware.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/lbpcascades/lbpcascade_frontalface_improved.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/lbpcascades/lbpcascade_frontalcatface.xml
-- Installing: /home/hcq/document/opencv/share/OpenCV/lbpcascades/lbpcascade_frontalface.xml
-- Installing: /home/hcq/document/opencv/bin/opencv_traincascade
-- Set runtime path of "/home/hcq/document/opencv/bin/opencv_traincascade" to "/home/hcq/document/opencv/lib:/usr/local/cuda-8.0/lib64"
-- Installing: /home/hcq/document/opencv/bin/opencv_createsamples
-- Set runtime path of "/home/hcq/document/opencv/bin/opencv_createsamples" to "/home/hcq/document/opencv/lib:/usr/local/cuda-8.0/lib64"
-- Installing: /home/hcq/document/opencv/bin/opencv_annotation
-- Set runtime path of "/home/hcq/document/opencv/bin/opencv_annotation" to "/home/hcq/document/opencv/lib:/usr/local/cuda-8.0/lib64"
-- Installing: /home/hcq/document/opencv/bin/opencv_visualisation
-- Set runtime path of "/home/hcq/document/opencv/bin/opencv_visualisation" to "/home/hcq/document/opencv/lib:/usr/local/cuda-8.0/lib64"
-- Installing: /home/hcq/document/opencv/bin/opencv_interactive-calibration
-- Set runtime path of "/home/hcq/document/opencv/bin/opencv_interactive-calibration" to "/home/hcq/document/opencv/lib:/usr/local/cuda-8.0/lib64"
-- Installing: /home/hcq/document/opencv/bin/opencv_version
-- Set runtime path of "/home/hcq/document/opencv/bin/opencv_version" to "/home/hcq/document/opencv/lib:/usr/local/cuda-8.0/lib64"6）配置 library：
- 打开/etc/ld.so.conf.d/opencv.conf，在末尾加入 /usr/local/lib（有可能是个空文件）
- 执行命令：sudo ldconfig
- 编辑 /etc/bash.bashrc，加入如下路径：
PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig
export PKG_CONFIG_PATH（2018.01.05 更新）说明：要先看看 /usr/local/lib/pkgconfig 这个路径下有没有 pkgconfig，本人使用的是 Anaconda2 的python，所以 pkgconfig 的路径在 /home/gtx/opencv/lib/pkgconfig。也就是说，我使用的路径如下：
# added by hcq 20180104
# opencv
PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/home/gtx/opencv/lib/pkgconfig
export PKG_CONFIG_PATH
7）安装完毕，测试 OpenCV
cd opencv/samples/ # 切换到 opencv/samples 目录下sudo cmake . # 在samples目录下进行 cmake
如果在 cmake 的过程中出现如下问题，则需要修改 samples 目录下的 CMakeLists.txt 文件：
CMake Error at CMakeLists.txt:55 (find_package):
By not providing "FindOpenCV.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "OpenCV", but
CMake did not find one.
Could not find a package configuration file provided by "OpenCV" with any
of the following names:
OpenCVConfig.cmake
opencv-config.cmake
Add the installation prefix of "OpenCV" to CMAKE_PREFIX_PATH or set
"OpenCV_DIR" to a directory containing one of the above files. If "OpenCV"
provides a separate development package or SDK, be sure it has been
installed.
-- Configuring incomplete, errors occurred!CMakeLists.txt 修改后如下所示：
cmake_minimum_required(VERSION 2.8)
project(samples C CXX)
option(BUILD_EXAMPLES "Build samples" ON)
# add by hcq 20171118
set(OpenCV_DIR /home/hcq/document/opencv/my_build_dir)
find_package(OpenCV REQUIRED)重新 cmake 成功后，提示如下所示：
hcq@hcq-home:~/document/opencv/samples$ sudo cmake .
-- Found OpenCV: /home/hcq/document/opencv/my_build_dir (found version "3.3.1")
-- OpenCL samples are skipped: OpenCL SDK is required
-- Configuring done
-- Generating done
-- Build files have been written to: /home/hcq/document/opencv/samples继续进行 make 编译：
sudo make -j8 # 在 samples 目录下进行编译-- OpenCL samples are skipped: OpenCL SDK is required
-- Configuring done
-- Generating done
-- Build files have been written to: /home/hcq/document/opencv/samples
Scanning dependencies of target example_phase_corr
Scanning dependencies of target example_kmeans
Scanning dependencies of target example_ffilldemo
Scanning dependencies of target example_convexhull
Scanning dependencies of target example_detect_blob
Scanning dependencies of target example_intelperc_capture
Scanning dependencies of target cpp-tutorial-pnp_detection
Scanning dependencies of target example_connected_components
[ 0%] Building CXX object cpp/CMakeFiles/example_kmeans.dir/kmeans.cpp.o./cpp-example-facedetect lena.jpeg测试成功后，效果如下图所示：
遇到的问题及其解决方案：
hcq@hcq-home:~/document/opencv$ cmake .
CMake Error at CMakeLists.txt:11 (message):
FATAL: In-source builds are not allowed.
You should create a separate directory for build files.
-- Configuring incomplete, errors occurred!解决方案：https://stackoverflow.com/questions/45518317/in-source-builds-are-not-allowed-in-cmake
hcq@hcq-home:~/document/opencv/samples$ sudo cmake .
-- The C compiler identification is GNU 5.4.0
-- The CXX compiler identification is GNU 5.4.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at CMakeLists.txt:55 (find_package):
By not providing "FindOpenCV.cmake" in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by "OpenCV", but
CMake did not find one.
Could not find a package configuration file provided by "OpenCV" with any
of the following names:
OpenCVConfig.cmake
opencv-config.cmake
Add the installation prefix of "OpenCV" to CMAKE_PREFIX_PATH or set
"OpenCV_DIR" to a directory containing one of the above files. If "OpenCV"
provides a separate development package or SDK, be sure it has been
installed.
-- Configuring incomplete, errors occurred!
See also "/home/hcq/document/opencv/samples/CMakeFiles/CMakeOutput.log".（注意：本文是新建一个名为 “my_build_dir” 目录，而不是 Release）