This code sample shows the basics to display OpenCV's matrix (cv::Mat) within a Qt GUI. The code simply load the flughahn.jpg image from the assets/ directory and display it using the QLabel widget.
Within the python/ directory, you will see the same code written in Python.
To compile and run the code, you need to have Qt 5 installed on your computer. The code is successfully tested on the following environment:
- Mac OS X Mavericks
- Qt 5.3.0
- OpenCV 3.0.0
- Python 3.4.1
Open ImageViewer.pro and modify the variables to match with your system. For example, you might need to modify the paths for the includes and libraries especially if you're on Windows.
INCLUDEPATH += /usr/local/include
LIBS += -L/usr/local/lib -lopencv_core -lopencv_highgui -lopencv_imgproc -lopencv_imgcodecs
Change your working directory and compile the code by typing:
qmake
make
If everything is ok, it will produce an executable: ImageViewer (Linux), ImageViewer.exe (Windows), or ImageViewer.app (Mac). Run the executable and you will see the GUI like the screenshot above.
In ImageViewer.cpp, the code using relative path to locate the input image:
img = cv::imread("../assets/flughahn.jpg");
If the program cannot display the image and shows the "Cannot load the input image!" warning, try to use absolute path instead. For example:
img = cv::imread("/full/path/to/flughahn.jpg");