Building my code (below) returns error 'imread' is not a member of 'cv'.
I am using:
Ubuntu 11.04.
libcv is at 2.1.0-3ubuntu1
CMake as a build system (with only project(foo) and add_executable(foo main.cpp) in it.)
main.cpp:
#include <opencv/cv.h>
int main(int argc, char **argv) {
cv::Mat src = cv::imread("frame_original.png", 0);
return 0;
}`
What do I need to include to get cv::imread to work?
imread is part of OpenCV 2.1:
http://opencv.willowgarage.com/documentation/cpp/highgui_reading_and_writing_images_and_video.html?highlight=imread#imread
But where is it on my system? What do I need to include? Where can I find the documentation that tells me which header file I need from OpenCV to use a specific function?
You should include opencv/highgui.h.
You might have to actually include the OpenCV library and the headers in your CMake configuration file.
Especially looking at include_directories for the header files and target_link_libraries for the library itself
Related
I want to use CUDA/GPU in OpenCV in Visual Studio. For example, cuda::GpuMat. I successfully build OpenCV with the extra modules with CUDA enabled
I tried the following code
#include <string>
#include <opencv2/core/core.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/photo/cuda.hpp>
#include <opencv2/photo.hpp>
using namespace std;
using namespace cv;
int main(){
string imageName("input.bmp");
//CPU version
Mat image = imread(imageName.c_str(), IMREAD_GRAYSCALE);
//CUDA version
cuda::GpuMat imageGPU;
cuda::GpuMat downloadGPU;
Mat buff;
imageGPU.upload(image);
downloadGPU.download(buff);
imwrite("gpu.bmp", buff);
return 0;
}
But I get an unhandled exception error.
I originally downloaded OpenCV in C:\Users\me\Downloads\opencv
I then downloaded and installed the latest OpenCV extra modules with CUDA on in
In Property Pages->C/C++->General->Additional Include Directories, I have:
C:\Users\me\Downloads\opencv\build\include\opencv
C:\Users\me\Downloads\opencv\build\include\opencv2
C:\Users\me\Downloads\opencv\build\include\
In Property Pages->Linker->General->Additional Library Directories, I have:
C:\Users\me\Downloads\opencv\build\x64\vc15\lib
and in Property Pages->Linker->Input->Additional Dependencies, I have:
opencv_world343d.lib
opencv_world343.lib
what else am I supposed to include so I can get GpuMat to work properly?
Most of the cases, yes, but you need to know which library you need to add, it may be cufft.lib, cublas.lib, cudnn.lib, etc. It depends of the function you use inside your code.
Opencv includes a cmake include file that would set all of this up for you if you use cmake to build you VS test project. This file will be in the root of the opencv install directory, i.e. after building opencv running cmake --install or the equivalent in VS. The file is OpenCVConfig.cmake, and it would be included in the CMakeLists.txt file for your project. Then you would call FindPackage(OpenCV), which would locate the OpenCV install, setup a few variables, which you would then use to link against your app.
I can post a sample CMakeList.txt file if you feel that would help.
i am making a simple c++ program with openCV library included. Eclipse IDE recognises openCV commands and library locations, but when i try to build the project, compiler gives external error, referring to opencv.hpp or core.hpp file calling a "opencv2/core.hpp" path, which does not exist in opencv folder. I figured out that the problem is linked to the way core.hpp is called, but the library files are read-only.
From what i saw in opencv.hpp file, this relative "opencv2/[module].hpp" reference is not only for the core, but all other modules as well. There is no opencv2 folder inside the one to where openCV is installed at all, in fact.
I've tried reinstalling and remaking openCV with different making arguments, using a different IDE and including direct search folders in eclipse. The problem, apparently, lies in the files themselves, or the way it maybe gets installed in the system the wrong way. The problem persists on both my main ubuntu machine and the ARMbian orange pi.
i get this error when trying to include any openCV library that contains
#include "opencv2/[opencv module].hpp" in it
as a result, compilation is terminated with the error message stating "/usr/local/include/opencv4/opencv2/opencv.hpp:52:28: fatal error: opencv2/core.hpp: No such file or directory"
edit 1: GCC c++ compiler options are -Iusr/local/include/opencv4/opencv2 -O3 -Wall -c -fmessage-length=0 and linker's options are -L/usr/local/lib.
The code is a simple displayImage
#include <opencv4/opencv2/opencv.hpp>
#include <opencv4/opencv2/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
using namespace cv;
int main( int argc, char** argv )
{
Mat image;
image = imread( argv[1], 1 );
namedWindow( "Display Image", CV_WINDOW_AUTOSIZE );
imshow( "Display Image", image );
waitKey(0);
return 0;
}
edit 2: $ pkg-config --libs opencv does not see openCV as installed in the system, altho i've made sure to run make install and ldconfig on the path. This may be a signal of faulty installation, but this is just a sidenote, not entirely related to main problem. I have tried reinstalls and to different folders, but this also persists as well as a main problem
apparently, #sgarizvi 's comment was the answer. I just needed to set the include path to I/usr/local/include/opencv4 and it worked. After that, the error was fixed.
I am replying to my own question to close the case, as i cannot upvote/veryfy a comment
In your case, since your include path is /usr/local/include/opencv4/opencv2
Replace the first three lines
#include <opencv4/opencv2/opencv.hpp>
#include <opencv4/opencv2/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
by
#include <opencv.hpp>
#include <imgproc.hpp>
#include <highgui.hpp>
This question already has answers here:
What is an undefined reference/unresolved external symbol error and how do I fix it?
(39 answers)
Closed 7 years ago.
I am trying to read an image in OpenCV, like this:
#include <opencv2/core/core.hpp>
#include <opencv2/imgcodecs.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/opencv.hpp>
using namespace cv;
using namespace std;
int main (int argv, char **argc)
{
Mat image = imread("Foam_Image.jg", CV_LOAD_IMAGE_GRAYSCALE);
return 0;
}
But I get the following error:
undefined reference to cv::imread(cv::String const&, int)
It seems that OpenCV cannot find the libraries I included, maybe because I didn't link them correctly, or maybe there are some libraries missing. Does anyone know how to look for missing libraries or how to link the libraries in OpenCV?
If your operating system is any UNIX which has CMake, then it would be better for you to write a CMakelists.txt file as follows
cmake_minimum_required(VERSION 2.8)
project( DisplayImage )
find_package( OpenCV REQUIRED )
add_executable( DisplayImage DisplayImage.cpp )
target_link_libraries( DisplayImage ${OpenCV_LIBS} )
And just use
cmake .
make
./DisplayImage
to execute the program.
you can install CMake from the official repositories using your package manager
In case your operating system is Windows, install CMake and set compiler options as Visual Studio (your version). Also add the OpenCV path to your system path, if not already done.
More instructions here :
http://docs.opencv.org/doc/tutorials/introduction/windows_install/windows_install.html
After digging for hours on this, I finally need some expert help.
I am new to cmake and trying to port my Visual Studio 2008 project to cmake.
My project uses opencv, qt and boost libraries.
Now I have managed to run simple cmake examples with opencv and qt but I am stuck with boost.
The bottleneck is this: CMake finds the correct boost version, finds the libraries and gives no error while configuration.
But when I try to build the project using make, it gives me:
" fatal error: boost/smart_ptr.hpp: No such file or directory"
Assuming the configuration is done right, cmake should be able to find the boost include directories.
I have set BOOST_ROOT to the correct boost root directory and that's why configuration does not give errors. But what happens while running make? Am I missing something simple here? Need help desperately...
I am sorry if this is a stupid question.
Here's my CMakeLists.txt file:
cmake_minimum_required( VERSION 2.6 )
project (CMakeBoostTutorial)
find_package( Boost 1.46.1 COMPONENTS date_time REQUIRED)
link_directories ( ${Boost_LIBRARY_DIRS} )
include_directories ( ${Boost_INCLUDE_DIRS} )
add_executable ( helloworld helloworld.cc )
target_link_libraries (
helloworld
${Boost_LIBRARIES}
)
And here's my helloworld.cc:
#include <iostream>
#include <stdlib.h>
#include <boost/smart_ptr.hpp>
using namespace std;<br/>
int main(int argc, char *argv[]){
cout<<"Hello World";
return 0;
}
PS: This compiles and runs fine if I remove the #include <boost/smart_ptr.hpp> line
I'm not sure why this is, but 99% of the problems I have with programming in C++ have to do with the gcc linker.
I want to link the Qt library to a project in CodeLite. This is the code I have so far:
#include <QApplication>
int main(int argc, char *argv[])
{
return 0;
}
When I compile, I get the error
/Users/andrew/Dev/C++/COSC 102/elitecod/main.cpp:1:24: error: QApplication: No such file or directory
I have Qt installed (with Homebrew, Mac OS X Lion) in /usr/local/include. Why is this happening, and how can I fix this problem?
The error indicates it can't find the file QApplication. You need to add the Qt 'include' directory to the list of places the compiler should look for it and other header files.
A brief google seems to indicate you may have other problems with Qt, you might want to keep this link handy.