opencv学习笔记

1.从官网（http://opencv.org/）上下载源码，编译安装，编译通过，未发现错误。

2.编写了如下测试程序：

//showImage.cpp
#include "highgui.h"

int main( int argc, char **argv )
{
    IplImage *img = cvLoadImage( argv[1] );
    cvNamedWindow("Example1", CV_WINDOW_AUTOSIZE);
    cvShowImage("Example1", img);
    cvWaitKey(0);
    cvReleaseImage(&img);
    cvDestroyWindow("Example1");
    return 0;
}

编译：根据网上的文档，使用如下参数编译

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

提示错误，函数未定义：

showImage.cpp:(.text+0x1d): undefined reference to `cvLoadImage'
showImage.cpp:(.text+0x35): undefined reference to `cvNamedWindow'
showImage.cpp:(.text+0x49): undefined reference to `cvShowImage'
showImage.cpp:(.text+0x55): undefined reference to `cvWaitKey'
showImage.cpp:(.text+0x61): undefined reference to `cvReleaseImage'
showImage.cpp:(.text+0x6d): undefined reference to `cvDestroyWindow'
collect2: ld 返回 1

解决办法：必须指定链接目录和库。`pkg-config --cflags --libs opencv`貌似不起作用

g++ showImage.cpp -o showImage -I /usr/local/include/opencv -lopencv_highgui -lopencv_core

编译成功。

3.运行程序，发现出错

OpenCV Error: Unspecified error (The function is not implemented. Rebuild the library with Windows, GTK+ 2.x or Carbon support. If you are on Ubuntu or Debian, install libgtk2.0-dev and pkg-config, then re-run cmake or configure script) in cvNamedWindow................略

解决办法：根据提示安装libgtk2.0-dev，并且重新编译opencv的源码。然后再编译此程序，运行成功。

4.编译另一个播放AVI视频的程序：

//showAVI.cpp
#include "highgui.h"

int main(int argc, char** argv)
{
    cvNamedWindow("Example2", CV_WINDOW_AUTOSIZE);
    CvCapture* capture = cvCreateFileCapture(argv[1]);
    IplImage* frame;

    while(1)
    {
        frame = cvQueryFrame(capture);
        if(!frame)
          break;
        cvShowImage("Example2", frame);
        char c = cvWaitKey(33);
        if(c == 27)
          break;
    }

    cvReleaseCapture(&capture);
    cvDestroyWindow("Example2");
    return 0;
}

编译后，运行出错：

Gtk-WARNING **: Unable to locate theme engine in module_path: "pixmap"

解决办法：

sudo apt-get install gtk2-engines-pixbuf

重新编译opencv源码和此程序，发现能运行，但是无法读取avi视频，也无错误信息输出。

gdb跟踪调试后发现cvCreateFileCapture()函数返回NULL，再次google之后发现缺少ffmpeg。于是

sudo apt-get install ffmpeg

 重新编译后还是如此。cmake生成Makefile的时候认真阅读了输出信息，发现缺少很多依赖。

目前在逐一补充所需依赖...

真不明白为什么缺少这么多文件还可以完全opencv的源码编译....