Qt + OpenCV, simple example

[stampede]

Hi,

today I've found my old project I wrote some time ago. This is simple application that uses OpenCV to capture images from camera or video, optionally process them and displays in QLabel. I've decided to share it with community, made the code more self-explanatory, added some comments, especially explaining BGR24 IplImage to QImage conversion stuff (it can be done easier, but I think its better this way for "educational" purposes).
This app does not use separate threads for capturing or processing images, I think everything is as simple as possible.
I've seen many posts about using basic OpenCV with Qt, so maybe this will be useful for some "newbies".

I hope this helps someone.

[lam-ang]

Hi Stampede,
I'm new to QT and opencv, I'm tring to learn to use QT and opencv by following the example given by the book. But I have problem in pointing the directory. So I search and found your free example application. I have installed Opencv2.3 and I tried to edit the project file...and just want to see if it will run..but still I have the similar problem.

TEMPLATE = app
DESTDIR = bin
TARGET = cvexample
DEPENDPATH += . src/cpp src/h src/ui
INCLUDEPATH += . src/h
 
UI_DIR = build
MOC_DIR = build
 
build_pass:CONFIG(debug, debug|release){
	OBJECTS_DIR = build/debug
} else{
	OBJECTS_DIR = build/release
}
 
win32 {
        CV11_INCLUDE = C:/OpenCV2.3
        CV11_LIB = C:/OpenCV2.3/lib
        CV22_INCLUDE = C:/OpenCV2.3/modules
        CV22_LIB = C:/OpenCV2.3/build/bin
} else{
	CV11_INCLUDE = /usr/local/include/OpenCV
	CV11_LIB = /usr/local/lib/OpenCV
        CV22_INCLUDE = /usr/local/include/OpenCV2.3
        CV22_LIB = /usr/local/lib/OpenCV2.3
}
 
contains(cv,2){
        message(build with opencv 2)
	DEFINES += OPEN_CV_22
        INCLUDEPATH += $$CV22_INCLUDE/core/include/opencv2.3/core \
                                   $$CV22_INCLUDE/highgui/include/opencv2.3/highgui \
                                   $$CV22_INCLUDE/imgproc/include/opencv2.3/imgproc \
				   $$CV22_INCLUDE/core/include	\
				   $$CV22_INCLUDE/imgproc/include
	LIBS += -L$$CV22_LIB
	LIBS += -lopencv_highgui220 -lopencv_core220 -lopencv_imgproc220
} else{
	message(build with opencv 1.1)
	DEFINES -= OPEN_CV_22
	INCLUDEPATH += $$CV11_INCLUDE/cv/include $$CV11_INCLUDE/otherlibs/highgui $$CV11_INCLUDE/cxcore/include
	LIBS += -L$$CV11_LIB
	LIBS += -lcv -lhighgui -lcxcore
}
 
HEADERS += src/h/ImageCapture.h src/h/MainWidget.h
FORMS += src/ui/MainWidget.ui
SOURCES += src/cpp/ImageCapture.cpp src/cpp/MainWidget.cpp main.cpp

TEMPLATE = app
DESTDIR = bin
TARGET = cvexample
DEPENDPATH += . src/cpp src/h src/ui
INCLUDEPATH += . src/h

UI_DIR = build
MOC_DIR = build

build_pass:CONFIG(debug, debug|release){
	OBJECTS_DIR = build/debug
} else{
	OBJECTS_DIR = build/release
}

win32 {
        CV11_INCLUDE = C:/OpenCV2.3
        CV11_LIB = C:/OpenCV2.3/lib
        CV22_INCLUDE = C:/OpenCV2.3/modules
        CV22_LIB = C:/OpenCV2.3/build/bin
} else{
	CV11_INCLUDE = /usr/local/include/OpenCV
	CV11_LIB = /usr/local/lib/OpenCV
        CV22_INCLUDE = /usr/local/include/OpenCV2.3
        CV22_LIB = /usr/local/lib/OpenCV2.3
}

contains(cv,2){
        message(build with opencv 2)
	DEFINES += OPEN_CV_22
        INCLUDEPATH += $$CV22_INCLUDE/core/include/opencv2.3/core \
                                   $$CV22_INCLUDE/highgui/include/opencv2.3/highgui \
                                   $$CV22_INCLUDE/imgproc/include/opencv2.3/imgproc \
				   $$CV22_INCLUDE/core/include	\
				   $$CV22_INCLUDE/imgproc/include
	LIBS += -L$$CV22_LIB
	LIBS += -lopencv_highgui220 -lopencv_core220 -lopencv_imgproc220
} else{
	message(build with opencv 1.1)
	DEFINES -= OPEN_CV_22
	INCLUDEPATH += $$CV11_INCLUDE/cv/include $$CV11_INCLUDE/otherlibs/highgui $$CV11_INCLUDE/cxcore/include
	LIBS += -L$$CV11_LIB
	LIBS += -lcv -lhighgui -lcxcore
}

HEADERS += src/h/ImageCapture.h src/h/MainWidget.h
FORMS += src/ui/MainWidget.ui
SOURCES += src/cpp/ImageCapture.cpp src/cpp/MainWidget.cpp main.cpp

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When I compiled it says "C:\QtCvExample-build-desktop\..\QtCvExample\src\h\ImageCapture.h:16: error: cv.h: No such file or directory"
I know there are some link in this forum regarding opencv, but still I cant find what I'm looking for.

thanks in advance,
lam-ang

[stampede]

If you are using OpenCV 2.2 or 2.3, you need to run qmake cv=2 and then make, because by default it will include and link to OpenCV 1.1 (btw. its in README ).
What does it print when you run qmake ? Probably "build with opencv 1.1", right ?

[lam-ang]

Hi, thanks..hmm I think I better do some more reading in order follow your suggestion...I appreciate the help. I'll get back, as soon I got it.

regards,
lam-ang

[lam-ang]

Hi, I have a question, I appoligize if this is so obvious, but I'm really struggling to learn QT. And I came back to post it here because I feel I'm not going anywhere..I was reading "OpenCV 2 Computer application Porgramming cookbook". The first exercise in the book is to display an image. But I found out my QT and Opencv configuration is not correct. I tried to search into this forum and found this useful example(by stampede) that I will gain from but obviously I dont have any idea how to do the procedure as suggested, I must use qmake and make ( tried to read some document) but I was getting lost ..So here is my question.
1. How can I configure QT and OpenCv using qmake and make?
Before trying the "QtCvexample" I want to try to display an image to the screen, please see my attachemnt. I have Qt 4.7.3 and OpenCv2.3 installed

Thanks in advance,
lam-ang