OpenCV cvLoadImage() does not load images in visual studio debugger? - c++

I am trying to work out a simple hello world for OpenCV but am running out of ideas as to why it is not working.
When I compile and run this code:
#include <cv.h>
#include <highgui.h>
int main(int argc, char* argv[])
{
IplImage* img = cvLoadImage( "myjpeg.jpg" );
cvNamedWindow( "MyJPG", CV_WINDOW_AUTOSIZE );
cvShowImage("MyJPG", img);
cvWaitKey(0);
cvReleaseImage( &img );
cvDestroyWindow( "MyJPG" );
return 0;
}
I get a grey box about 200x200 instead of the indicated .jpg file. If I use a different jpg I get the same kind of window, and if I put an invalid filename in, I get a very tiny window (expected).
I am using Visual Studio 2008 under Windows 7 Professional.
Most of the sample programs seem to work fine, so I am doubly confused how that code loads the sample jpgs just fine but in the code above it does not work (even tried the sample jpeg).
Update
The executables produced by compiling work fine, however the Visual Studio 2008 debugger loads a null pointer into img every time I try to run the debugger - regardless if the file location is implicit or explicit.


It really seems like there's a problem with the path to myjpeg.jpg since the current directory could be different when you're running under the debugger.
By default, the current directory that the Visual Studio debugger uses is the directory containing the .vcproj file, but you can change it in the project properties (Debugging -> Working Directory).
Are you 100% sure that you pass the absolute path correctly? Try to pass the same path to fopen and see if it also returns NULL. If so, then the path is incorrect.
If you want to see exactly what file is the library trying to open you can use Project Monitor with a filter on myjpeg.jpg.


Which version of OpenCV are you using? I've tried your code on the latest (OpenCV2.0) and it works fine. You can download OpenCV2.0 from here.
If you want the latest build, you can get check it out with SVN from here.


Try to add HAVE_JPEG into preprocessor definitions.


I encountered the same problem. The Debug version does not load the image, but when I compile and link it as a Release it works. I hope this helps

Related

Error in opencv function in .exe file but not in debug nor release

One more time, I want to ask for your help after long and unfruitful researches.
I have developped an app using OpenCV which works very well is Visual Studio in debug and release mode.
I tried to deploy it, but i get a fatal error when I start the .exe. By using a log file and doing tests, I figured out the problem was in function cv::resize in the following code :
Mat logo = imread("lena.png");
cv::resize(logo, logo, Size(), 0.55, 0.55, INTER_CUBIC);
I found very weird that i can call cv::imread (and cv::Mat) without throwing exception but not resize.
If I try to run the .exe created by the compilation in release mode, i get the following errod code : 0xc000007b.
I read it could be a problem of compatibility between 32/64-bits dll, without being able to solve it. I try to build a 64-bits appplication. The path for opencv lib is define like this : C:\opencv\build\x64\vc14\lib
Thank you for your help,
Valentin B

OpenCV program compiles but doesn't run

I am working on Windows 8 with OpenCV 2.4.13 and MinGW 4.9.
I wrote a simple and small opencv program to check if everything was installed properly. Following is the code:
#include <opencv2/highgui/highgui.hpp>
int main () {
printf("in main\n");
for (int i = 0; i<10; i++) {
printf("here\n");
IplImage * image = cvLoadImage("C:/{...}/test.jpg");
cvReleaseImage(&image);
}
return 0;
}
I compiled it with the following command at the command prompt:
g++ -o test test.cpp -LC:\{...}\opencv\build\x64\vc11\lib -lopencv_core2413 -lopencv_highgui2413 -IC:\{...}\opencv\build\include
{...} is the path to the specified folder/file.
This command runs properly and compilation is successful without any errors. However, when I run it with:
test
in main and one here gets printed after which I get the error message as 'test.exe has stopped working. Windows is looking for a solution.'
What all I have tried:
For installation of OpenCV, ran the downloaded opencv executable file (which extracts all files) and added the system variable OPENCV_DIR and edited the system PATH for location of DLLs (which reside in %OPENCV_DIR%\bin) as per:
http://docs.opencv.org/2.4/doc/tutorials/introduction/windows_install/windows_install.html#installation-by-using-the-pre-built-libraries
Tried adding the required DLLs in the same directory as the .exe.
Tried doing the whole thing from vc12 directory.
After the error message appears, it gives an option of debugging. On pressing that, the Just In Time Debugger opens up and says 'An unhandled win32 exception occurred in test.exe'. I googled this and tried inspecting the registry key as directed here
https://support.microsoft.com/en-us/kb/811191
but it was already properly set. So, there was nothing for me to change in that.
Nothing is working for me at all. Please let me know if any more information is required. I'm desperately looking for a solution to this.

For those who might be encountering the same problem, I compiled the program with OpenCV dynamic (.dll) libraries instead of the .lib files and it ran just fine at runtime for some reason.

Why is imread() always returning null data?

Here is my code:
#include<opencv\cv.h>
#include<opencv\highgui.h>
using namespace cv;
using namespace std;
int main()
{
Mat src;
//src.create(200,500,CV_8UC3);
src = imread( "a.bmp", 1 );
namedWindow( "Display window", WINDOW_AUTOSIZE );
if(!src.data)
cout<<"Could not open or find the image" << std::endl ;
else
imshow( "Display window", src);
waitKey(0);
return 0;
}
It is always executing the if part
when I am using src.create instead of imread() it shows an empty image.

To debug your issue you should try to confirm that the image path is correct.
As suggested in the comments, try specifying the full absolute path of the file. Remember to to use escape slashes if you are on windows (e.g. c:\a.bmp will need to be "c:\a.bmp")
OR
If you are executing your application from Visual Studio then you can configure the working directory to be that of the bitmap too! (OpenCV cvLoadImage() does not load images in visual studio debugger?)
You can also try using cvLoadImage instead of imread. If cvLoadImage can open the file then it is possible that you have a mix of release and debug libraries causing you an issue as per:
OpenCV imread(filename) fails in debug mode when using release libraries

The OpenCV documentation has mentioned imread() would return an empty matrix ( Mat::data==NULL ) if the image file cannot be read.
http://docs.opencv.org/modules/highgui/doc/reading_and_writing_images_and_video.html#imread
You should check if the "a.bmp" file is in your current working directory. The IDE (visual studio) may set executable's working directory (Debug/... Release/... ) on purpose. Using an absolute path to "a.bmp", or starting executable in an expected directory from command line would also help, provided that "a.bmp" is a valid BMP file and you have the right file system permission to read it.

I was having the same issue on visual studion and imread returning null data.
img = cv::imread("c:\\data\\a.bmp",1);
Note the \\ delimiters to enable windows to correctly parse the path.

Your opencv libs should match the configi.e., Debug or Release of your application in Visual Studio or whatever build you are using (If you are using pre-built binaries) for WINDOWS.

C++ Compilation introduce errors

I have a multi-threaded C++ windows project in Visual Studio 2010 which uses Qt (5.1.1) and OpenCV (2.4.8). When I build it in Debug mode everything runs fine, but when I build it in Release mode the program crashes. Both configurations are almost identical (just in Release I have Multi-threaded DLL /MD and in Debug Multi-threaded Debug DLL /MDd), I disabled optimizations for the Release, and even enabled debug to catch the error. What's most weird is that the same piece of code that crashes, runs just fine in another console project.
The error is internal to OpenCV's code, it's not related to my code, my code is just:
void MyProject::findEllipses(QImage &frame, vector<RotatedRect> &ellipses)
{
Mat image = Mat(frame.height(), frame.width(), CV_8UC4, frame.scanLine(0));
cvtColor(image, image, CV_RGB2GRAY);
GaussianBlur(image, image, Size(3, 3), 0, 0, 4);
threshold(image, image, treshVal, 255, THRESH_BINARY);
vector<vector<Point> > contours;
Mat contoursImage = image.clone();
findContours(contoursImage, contours, CV_RETR_LIST, CV_CHAIN_APPROX_NONE, Point(0, 0));
// ....Mode Code
As I said in Debug the code runs without a problem, findContours calls _contours.create(total, 1, 0, -1, true); (in line 1720 of OpenCV's contours.cpp) and moves on that method....BUT in Release, when I step into _contours.create(total, 1, 0, -1, true), instead of executing that method, the program jumps to void _OutputArray::clear() const (line 1674 of matrix.cpp) and get's trapped in there, because it calls int k = kind(); in it's first line, which, instead of calling cv::kind(), calls:
int _InputArray::type(int i) const
{
int k = kind();
Which calls againg kind() which again calls type() (instead of kind()as it should), making an infinite recursive loop, bringing a stack overflow.
I tried to make a new Visual Studio 2010 project to see if this is a project creation problem but the problem persisted.
My guess is that the function adresses are wrong in release mode so when it tries to call create(), it instead calls another address, making a mess in the stack, but that's just my guess. At first I will blame OpenCV release dlls, but, as I said, in another console project that only runs that particular code, the code runs fine in bot build modes. I don't see how my other threads and code can trigger this behavior, since the error goes down to a wrong function call in OpenCV.
This is way beyond my knowledge and I have no idea how to fix this, I appreciate all the help I can get on this problem, because I already exausted all my ideas to fix it....
EDIT :
I made a small project so anyone can see what's happening.
The files are in:
https://app.box.com/s/3owljl44emv57erinrf8
In order to run it, you have to have OpenCV 2.4.8 and Qt 5.1.1 and configure the Visual Studio 2010 project to get the include files from the right places. In the resources folder there is a image that will be loaded, and in the SaraVisualControl.cpp line 20, you have to place the right path to the image, sorry I didnt made this automatic, but I was in a hurry to pack this in a small project. Any other questions about how to run it, please let me know.
EDIT 2
I found this old thread: http://code.opencv.org/issues/2218 the user appears to have the same problem as I have, and just running CMake with OPENCV_CAN_BREAK_BINARY_COMPATIBILITY turned off appears to solve it. But this option is no longer present in the new versions of OpenCV, as stated here http://code.opencv.org/issues/2358. Does anyone knows the implications of this and how it may be related?

I encountered similar symptoms in the past, when mixing VC runtime versions. If you're working in VC2010 and OpenCV 2.4.8 was built on 2012 or even 2013, your ABI does not match. E.g., the layout in memory of std::vector is different, maybe the order of some methods in a vtable somewhere changed, etc.
An easy way to test this is to inspect the 'Modules' window while debugging and look for runtime dll's of a later version. Yours is msvcr100d.dll, if you see msvcr110d or 120d - this might be the source.
(assuming both you and OpenCV link dynamically to the CRT - which I cannot tell).

The debug and release are different in memory allocations. Usually in Debug mode that allocs are bigger.
May be you abuse some openCV call, but you don't aware of it.
I would do next actions:
Validate that the frame is ok. May be it is too big, or width or height are not initiated;
Validate that after next line the image var is OK
Mat image = Mat(frame.height(), frame.width(), CV_8UC4, rame.scanLine(0));
Is it OK to call cvtColor while the 1st and 2nd param are the same (may be you abuse the CV here)
Is it OK to call GaussianBlur while the 1st and 2nd param are the same? Try to put different 2nd param
The same is with threshold function call
Check that after image.clone call, the countoursImage is a valid matrix.

I'm guessing: In addition to checking that the libraries are all correct themselves, check that you specify all libraries in the same order (in all builds). Otherwise, the linker might bind function names to different implementations during the final linker stage.

I had the same issue.I was using Qt 5.1.1 and opencv248 and my application was crashing after returning from findcontours. Turns out I was using the vc10 libs in the pro file and the corresponding dlls whereas the Qt compiler being used was msvc2013. Switching to the vc12 folder in opencv 248 solved the problem for me.

Have you checked your opencv libraries for Release version.
Opencv has different set of libraries for Release and Debug version. if you have accedently included debug libraries in the release mode. your code will compile with no error but will throw excecption when executed.
To check your libraries goto
Project->Properties->Configuration Properties->linker->Input->Additional Dependencies.
make sure none of your Opencv libraries ends with "d" for release mode.
library for Release : 'opencv_core248.lib'
library for Debug : 'opencv_core248d.lib'
notice the d at the end for debug mode.
I hope this would be helpful.

How to load xml cascade file in openCV 2.3.1

I try bulid face detect applicatyion on Visual Studio 2010 using C++ and OpenCV 2.3.1 library
So, I declaration String type and initialize:
String face_cascade_name = "haarcascade_frontalface_alt.xml";
Next, I create a object of class CascadeClassifier:
CascadeClassifier face_cascade;
And I load cascade:
if( !face_cascade.load(face_cascade_name) ){ printf("--(!)Error loading\n"); return -1; };
The project bulid and debugging without problem, but when I run application and application try load cascade program crash!
And I see this communication:
The program '[1288] OpenCV2.0.exe: Native' has exited with code -1 (0xffffffff).

I had the same problem with CascadeClassifier and FileStorage.
For example if you try this:
FileStorage fs(xml_fname, FileStorage::READ);
if (!fs.isOpened())
{
cout<<"can not read xml"<<endl;
}
Probably, it won't work.
In my case, I passed in VC++ from Debugging mode to Release mode, specified .lib files without d at the end (e.g. opencv_core231.lib) and it works now.

In my case(OSX 10.9), I input the whole path instead of simply "haarcascade_frontalface_alt.xml", like "/Users/xxx/Desktop/opencv-2.4.7/data/haarcascades/haarcascade_frontalface_alt.xml". Good Luck

In my case (win7 64, VS 10 express), changing file permissions for xml files solved the problem,
I added Everyone with full controll, and it worked.