原文：https://blog.csdn.net/Guet_Kite/article/details/78667175?utm_source=copy 
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接下来就是下载opencv了： 
下载地址：http://blog.csdn.net/yanzi1225627/article/details/47668021

下载好之后解压：unzip opencv-2.4.11.zip
cd opencv-2.4.11.zip
建两个文件夹来存放配置和安装路径：
sudo mkdir /usr/local/opencv/install_opencv -d
sudo mkdir /usr/local/opencv/config_opencv -d

然后用cmake配置：
sudo cmake-gui

在where is the source code:里写上opencv的源文件路径 
在where to build the binaries:里面写上作为cmake编译arm版本的工作目录 
然后点击configure

这里generator保持为Unix Makefiles，然后选择第四个选项：Specify options for cross-compiling 
最后点击Next

这里Targeting System选的是Linux（之前我选的是arm-linux，有点坑，选这个没有V4L支持），
接着就是选择工具链了，我用的是友善的4.4.3的工具链，Compliers写的是交叉编译工具 arm-linux-gcc、arm-linux-g++
Target Root写的是交叉编译工具 arm-linux-g++/gcc 的所在包含文件夹
最后点击 Finish即可

然后中间红色的配置里：
取消WITH_GTK
取消WITH_TIFF
选择WITH_QT
GTK配置比较麻烦，我Ubuntu之前就配置好有QT了，所以我们取消掉，直接用QT最GUI。如果没有配置有QT，那还是不选吧。
最后点击Configure，会发现有错误：Error in configuration process,project files may be invalid
CMake Warning at cmake/OpenCVFindLibsGUI.cmake:18 (find_package):
By not providing “FindQt5Core.cmake” in CMAKE_MODULE_PATH this project has
asked CMake to find a package configuration file provided by “Qt5Core”, but
CMake did not find one.

Could not find a package configuration file provided by “Qt5Core” with any
of the following names:
Qt5CoreConfig.cmake
qt5core-config.cmake
第一个是一个warning，不管，下一个是error，说的是”Qt5Core”没找到。
我的QT安装路径是：/work/qt/my_qt/
所以直接把/work/qt/my_qt/lib/cmake/Qt5Core 填到Qt5Core_DIR选项即可，
同理，底下几个选项也要填上，Qt5Gui_DIR、Qt5Test_DIR等…….

最后点击Configure无误后，点击Generate按钮就会在/usr/local/opencv/install_opencv目录生成Makefile

cd /usr/local/opencv/config_opencv
修改安装opencv的路径：
sudo vi CMakeCache.txt
找到：CMAKE_INSTALL_PREFIX:PATH=/usr/local
修改为：CMAKE_INSTALL_PREFIX:PATH=/usr/local/opencv/install_opencv
这是我自己的安装路径。

接着sudo make编译
最后把/usr/local/opencv/install_opencv/lib下文件移植到开发板根文件lib下

好了，我们测试下： 
从网上找到一个测试例子,然后修改下，test.cpp：

#include <cv.h>

#include <cxcore.h>

#include <highgui.h>

#include <iostream>

using namespace std;

int main(int argc, char **argv)

{

         CvCapture* capture = NULL;

         IplImage* frame = NULL;

         if(!(capture = cvCaptureFromCAM())) {

                 cout<<"Can not open camera.\n"<<endl;

                 return -;

         }

         cvNamedWindow("video", );

         while(frame = cvQueryFrame( capture )){

                  cvShowImage("video",frame);

                  cout<<"have capture\n"<<endl;

         }

         cout<<"no have capture\n"<<endl;

         cvDestroyWindow("video");

         cvReleaseCapture(&capture);

         return ;

}

编译：

arm-linux-g++ -I/usr/local/opencv/install_opencv/include/opencv/ -L/usr/local/opencv/install_opencv/lib/ -lcv -lcxcore -lhighgui -lpthread -lrt -o test test.cpp

出现： 
test.cpp:21: note: the mangling of ‘va_list’ has changed in GCC 4.4 
在GCC 4.4里，’va_list’已经被改变了，所以我们编译时，要加上 -Wno-psabi选项：

arm-linux-g++ -Wno-psabi -I/usr/local/opencv/install_opencv/include/opencv/ -L/usr/local/opencv/install_opencv/lib/ -lcv -lcxcore -lhighgui -lpthread -lrt -o test test.cpp

那么，这样可以了吗？
不行！出现：
/usr/local/arm/opt/FriendlyARM/toolschain/4.4.3/bin/../lib/gcc/arm-none-linux-gnueabi/4.4.3/../../../../arm-none-linux-gnueabi/bin/ld: cannot find -lcv
collect2: ld returned 1 exit status
这里提示lcv找不到，为什么呢？
还是我之前说的，网上的文章都是几年前的了，好老了。
打开我们opencv的lib可以看下，根本没有这些个库了，

所以提示自然找不到，所以要改成我们现在opencv的库：

arm-linux-g++ -Wno-psabi -I/usr/local/opencv/install_opencv/include/opencv/ -L/usr/local/opencv/install_opencv/lib/ -lopencv_core -lopencv_highgui -lpthread -lrt -o test test.cpp

出现两个warning：
/usr/local/arm/opt/FriendlyARM/toolschain/4.4.3/bin/../lib/gcc/arm-none-linux-gnueabi/4.4.3/../../../../arm-none-linux-gnueabi/bin/ld: warning: ../../lib/libopencv_imgproc.so, needed by /usr/local/opencv/lib_opencv/lib//libopencv_highgui.so, not found (try using -rpath or -rpath-link)
/usr/local/arm/opt/FriendlyARM/toolschain/4.4.3/bin/../lib/gcc/arm-none-linux-gnueabi/4.4.3/../../../../arm-none-linux-gnueabi/bin/ld: warning: ../../lib/libopencv_core.so, needed by /usr/local/opencv/lib_opencv/lib//libopencv_highgui.so, not found (try using -rpath or -rpath-link)

将需要到的那三个.so文件:libopencv_core.so libopencv_highgui.so libopencv_imgproc.so将这些库复制到编译器的lib中：

sudo cp -d *libopencv_core* *libopencv_highgui* *libopencv_imgproc*  /usr/local/arm/opt/FriendlyARM/toolschain/4.4./arm-none-linux-gnueabi/lib

以上借用风筝大神博客

本人编译使用命令

arm-cortex_a8-linux-gnueabi-g++ -Wno-psabi -I/usr/local/opencv/install_opencv/include/opencv/ -L/usr/local/opencv/install_opencv/lib/ -lopencv_core -lopencv_highgui -lpthread -lrt -o video1 video1.cpp 

然后把编译出来的test文件放到开发板上执行。

测试二：

 #include<opencv2/core/core.hpp>

 #include<opencv2/highgui/highgui.hpp>

 #include<iostream>

 using namespace cv;

 using namespace std;

 int main( )

 {

     //载入图片

     Mat image= imread("girl.jpg");

     Mat logo= imread("fly.jpg");

     //定义一个Mat类型，用于存放，图像的ROI

     Mat imageROI;

     imageROI= image(Rect(,,logo.cols,logo.rows));//定义一个左上角点坐标为(_x, _y)的cols*rows矩形窗口

     //将logo加到原图

     //参数：图、权重、图、权重、添加的常数项、输出图

     addWeighted(imageROI,0.5,logo,0.3,.,imageROI);     

     cout << "start add picture......\n" << endl;

     //输出一张jpg图片到工程目录下

     imwrite("fly_girl.jpg",image);  

     waitKey();  

     return ;

 }  

Makefile：

 CC  = arm-linux-g++

 LFLAGS  = -Wno-psabi

 LIBS    = -L/usr/local/opencv/install_opencv/lib/ -L/work/qt/my_qt/lib

 CPPFLAGS    = -lQt5Widgets -lQt5Gui -lQt5Core -lpthread -lopencv_core -lopencv_highgui -lpthread -lrt

 LINC     += -I/usr/local/opencv/install_opencv/include/opencv/

 objs := open

 out := open

 $(out):$(objs).cpp

     ${CC} ${LFLAGS} ${LIBS} ${LINC} ${CPPFLAGS} -o $@ $^

 clean:

     rm $(out)

这是girl.jpg图：

这是fly.jpg图：

这是使用opencv合成的效果图：