I am using openCV for the first time, I have followed the installation guide(for linux with eclipse CDT) and trying to run the sample program, but I keep getting the following error message.
terminate called after throwing an instance of 'std::logic_error'
what(): basic_string::_S_construct null not valid
#include<cv.h>
#include<highgui.h>
using namespace cv;
int main( int argc, char** argv ){
Mat image;
image = imread( argv[1], 1 );
if( argc != 2 || !image.data )
{
printf( "No image data \n" );
return -1;
}
namedWindow( "Display Image", CV_WINDOW_AUTOSIZE );
imshow( "Display Image", image );
waitKey(0);
return 0;
}
I got this same problem after finally getting my OpenCV libraries to link. You are probably running the executable without an argument resulting in argv[1] to be Null when you try and do an image read. The solution for me, on eclipse, was to call the file directly with an argument in command prompt; "testOpenCV.exe imageFile.png". I obviously was using windows, but simply calling the executable with an argument, in terminal for your linux, should work.
Related
I am compiling on Ubuntu 14.04 using OpenCV 3.1. When trying to open a video file it gives this error:
"Cannot open the video file"
I installed everything i could install : ffmpeg etc. Haven't found a solution checking out similar questions on StackOF.
What do ?
cv::VideoCapture cap(argv[1]);
Where argv[1] is the file name in the same directory as the executable.
In case your constructor is failing, you may want to use the .open() method. So, if you want to open a file that is called "myVideo.mp4" that is in the folder of your project, you would do the following:
cv::VideoCapture cap;
cap.open("myVideo.mp4");
For more detailed informations about this method, check this documentation link
Also, the book Learning OpenCV 3, from the O'Rilley media, on page 26 gives you a good example. Here is a Gist that I made to give you as an example.
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>
int main() {
cv::VideoCapture cap;
cap.open("myVideo.mp4" );
cv::namedWindow( "myVideo", cv::WINDOW_AUTOSIZE );
cv::Mat frame;
while(true) {
cap >> frame;
if( frame.empty() ){
std::cout << "Could not load the video frames. \n";
break;
}
cv::imshow( "myVideo", frame );
if( cv::waitKey(27) >= 0 ){
std::cout << "Escape pressed \n";
break;
}
}
return 0;
}
I am configuring openCV on my eclipse and can't run the simple example given in the openCV tutorial, i followed the exact steps as in here
#include <opencv2/opencv.hpp>
#include <iostream>
using namespace cv;
int main( int argc, char** argv )
{
Mat image;
image = imread( argv[1], 1 );
if( argc != 2 || !image.data )
{
printf( "No image data \n" );
return -1;
}
namedWindow( "Display Image", WINDOW_AUTOSIZE );
imshow( "Display Image", image );
waitKey(0);
return 0;
}
The project settings are
It gives me the following errors:
cannot find -lopencv_contrib C/C++ Problem
make: *** [projectname] Error 1 C/C++ Problem
recipe for target 'projectname' failed makefile /faa/Debug line
45 C/C++ Problem
When i removed opencv_contrib the errors become:
./src/projectname.o: undefined reference to symbol
'_ZN2cv6imreadERKNS_6StringEi' C/C++ Problem
make: *** [projectname] Error 1 C/C++ Problem
recipe for target 'projectname' failed makefile /projectname/Debug line 45 C/C++ Problem
I removed the opencv and reinstalled it again but this time i used Debug instead of Release in
cmake -D CMAKE_BUILD_TYPE=Debug -D CMAKE_INSTALL_PREFIX=/usr/local ..
and it worked.
I copy this code from openCV2 book and this code have argc and argv as arguments that I don't know what they are and why assign to 1 (argc=1) and terminate debugging ...my problem that why argc=1? And how I can fix it? because my argc should be 2 (argc==2)...
#include <stdio.h>
#include <opencv2/opencv.hpp>
using namespace cv;
int main( int argc, char** argv )
{
if ( argc ! = 2 )
{
printf( " usage: DisplayImage.out <Image_Path>\n" );
return - 1;
}
Mat image;
image = imread( argv[ 1], 1 );
if ( ! image.data )
{
printf( " No image data \n" );
return - 1;
}
namedWindow( " Display Image" , WINDOW_AUTOSIZE );
imshow( " Display Image" , image);
waitKey( 0);
return 0;
}
I try to wrote this code without argc and argv but the debugger has a runtime error that i think its cause be argc.
If you run it by command line, you can call it as
DisplayImage "path_to_image"
If you want to run from VS, be sure to add the "path_to_image" in your command arguments:
PROJECT -> Properties -> Configuration Properties -> Debugging
Put the "path_to_image" in Command Arguments
Be sure that "path_to_image" is a valid path, check here for reference.
As already pointed out in comments, it's a very bad example!
OpenCV 3.0.0 has also CommandLineParser for more complex input arguments.
I found that this question has been asked many times here, but I haven't found any solution or work-around to this problem. Here's my code (copied from here: http://docs.opencv.org/doc/tutorials/introduction/display_image/display_image.html):
#include <iostream>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
using namespace cv;
using namespace std;
int _tmain(int argc, char** argv)
{
if( argc != 2)
{
cout <<" Usage: display_image ImageToLoadAndDisplay" << endl;
return -1;
}
Mat image;
image = imread(argv[1], CV_LOAD_IMAGE_COLOR); // Read the file
if(! image.data ) // Check for invalid input
{
cout << "Could not open or find the image" << std::endl ;
return -1;
}
namedWindow( "Display window", WINDOW_AUTOSIZE ); // Create a window for display.
imshow( "Display window", image ); // Show our image inside it.
waitKey(0); // Wait for a keystroke in the window
return 0;
}
I compiled this using Visual Studio 2008 and 2010, and got different results (both don't work). The program compiled using VS 2008 has run-time error at imread(), and the other displays the message "Could not open or find the image".
Anybody can help me with this?
The problem here is your main() function._tmain does not exist in C++. main does.
_tmain is a Microsoft extension. Here is a nice explanation of these two methods.
Further more if you want to add default argument in Visual studio please follow these steps.
Right click your project in Solution Explorer and select Properties from the menu
Go to Configuration Properties -> Debugging
Set the Command Arguments in the property list.
Hope this solves your problem!
#include <iostream>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
using namespace cv;
using namespace std;
int main(int argc, char **argv)
{
if( argc != 2)
{
cout <<"No Commandline Aurgument Found!: Usage: display_image ImageToLoadAndDisplay" << endl;
return -1;
}
Mat image;
image = imread(argv[1], CV_LOAD_IMAGE_COLOR); // Read the file
if(! image.data ) // Check for invalid input
{
cout << "Could not open or find the image" << std::endl ;
return -1;
}
namedWindow( "Display window", WINDOW_AUTOSIZE ); // Create a window for display.
imshow( "Display window", image ); // Show our image inside it.
waitKey(0); // Wait for a keystroke in the window
return 0;
}
set argv[1] to be a known image page "C:\test.jpg"
Ok, Ive read all the comments and I'm going to answer the main question along with the sub questions.
Why Doesn't my Code Work in VS2008?
The reason your code doesn't work in VS2008 is because you are using the compiled libraries for 2010, at least I think this is a pretty accurate assumption. If you want to be completely accurate then build the libraries, for the compiler you are using.
What is tmain & what is main
This stack overflow question answers the subject a lot better than I ever could, but effectively it is a windows specific main and does not actually exist in C++. It get removes by the compiler on compile time and converter to main.
Can you please try this: Use known-to-work image and absolute path until it works so you can be sure that there is no problem with image or relative path.
download http://upload.wikimedia.org/wikipedia/en/2/24/Lenna.png to C:\Lenna.png
rename your main function to something else and try this: if it does not work, please tell me the displayed name of the output window.
#include <iostream>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
using namespace cv;
using namespace std;
int main(int argc, char **argv)
{
namedWindow( "Display window", WINDOW_AUTOSIZE ); // Create a window for display.
Mat image;
image = imread("C:/Lenna.png", CV_LOAD_IMAGE_COLOR); // Read the file
if(! image.cols ) // Check for invalid input
{
cout << "Could not open or find the image. Press any key to exit." << std::endl ;
cv::waitKey(0)
return -1;
}
imshow( "Display window", image ); // Show our image inside it.
waitKey(0); // Wait for a keystroke in the window
return 0;
}
Please try this and if it does not work, please tell me the displayed name of the output window.
I'm trying to run OpenCV on OSX in Xcode. I have downloaded the code from github. And used cmake to compile it.
Next I created a new Xcode project with the following code:
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
using namespace cv;
using namespace std;
int main( int argc, char** argv )
{
if( argc != 2)
{
cout <<" Usage: display_image ImageToLoadAndDisplay" << endl;
return -1;
}
Mat image;
image = imread("img.jpg"); // Read the file
if(! image.data ) // Check for invalid input
{
cout << "Could not open or find the image" << std::endl ;
return -1;
}
namedWindow( "Display window", WINDOW_AUTOSIZE );// Create a window for display.
imshow( "Display window", image ); // Show our image inside it.
waitKey(0); // Wait for a keystroke in the window
return 0;
}
Next I've set the header search path to: /usr/local/include
After that I've added the libraries from /usr/local/lib in the "Build Phases" as seen in the screenshot below.
(source: opencv.org)
However, when I try to run I get the following error:
ld: library not found for -lopencv_core.3.0.0
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Did I mis something?
In search for header path,
double tap the property. if you see the empty string
don't enter there,
slowly tap twice as it pop up a new list of properties
add the new one under the values press enter
still if its not working ,
check your string
You should add /usr/local/lib to the library search paths as well.