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    • UNSOLVED QTQuick, OpenCv and Gstreamer frame capturing
      QML and Qt Quick • opencv gstreamer1.0 • • ElifOzkan  

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    • UNSOLVED .open() unable to open stream in packaged application
      General and Desktop • opencv deploy problems • • BigBen  

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      @BigBen This sounds like you would be best looking for openCV's VideoCapture.open() questions? Maybe whatever it does requires certain files in certain places which are not present/found on the other system, either openCV runtime files or the file you are trying to open?
    • UNSOLVED LNK2019 y LNK1120 using sapera sdk for camera genie nano y openCV
      3rd Party Software • opencv buffer lnk2019 sapera lnk1120 • • ADR_PT  

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      Hi and welcome to devnet, Are you sure you are linking all the required libraries ? Are they all from compatible compilers ?
    • UNSOLVED Digital zoom for live stream
      General and Desktop • c++ opencv camera rtsp digital-zoom • • BigBen  

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      @BigBen Yes, you always need to write a new class which derives from the base class if you need to override a virtual method, as QWidget::paintEvent(). The Analog Clock Example illustrates overriding paintEvent(). There will be hundreds of other examples online.
    • UNSOLVED How to fix the "unresolved external symbol" error during OpenCV 4.5.5 building with Qt 6.3.0 support in Visual Studio 2019?
      General and Desktop • opencv qt 6.3.0 • • Elversu  

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    • UNSOLVED When using opencv, the Qt project crashes
      General and Desktop • opencv crash app • • md3848  

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      I am wondering whether there's some bad interaction between the 2017 build of Qt and your 2019 build of OpenCV. There should not as VS 2019 is backward compatible with 2017.
    • UNSOLVED Right format to use to display an image cv::Mat CV_32F normalized
      General and Desktop • image opencv qt image • • Rui f  

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      Hi and welcome to devnet, You can't jump from a 32bit float image to 16bit integer one like that. Convert your OpenCV image to 16 bit before making a QImage out of it.
    • UNSOLVED “qimage out of memory returning null image” after working for 60 QImages
      3rd Party Software • qimage opencv qpixmap • • tim5  

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      Hi, You should check your video file, but as I wild guess, it's likely a FullHD video which is 1920 * 1024. Since you are creating a RGB QImage out of it, it's already weighing about 6MB per image. QPixmap is meant to be optimised for rendering and thus the backing memory used might even be larger for, for example, alpha channel handling. Depending on what else you do with your application and these images you can pretty quickly hit memory limits if your application is 32bit.
    • UNSOLVED 'opencv2/opencv.hpp' file not found
      General and Desktop • c++ opencv opencv cpp • • blackbox  

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      Lack INCLUDEPATH such as: INCLUDEPATH += /usr/local/include
    • SOLVED Live camera image using OpenCV showing in Qlabel crashes due to out of memory error
      General and Desktop • gui qimage c++ qt opencv qpixmap • • Imran Hassan  

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      Thank you all guys. Your suggestions and expert opinion helped a lot with solving the problem. QT forum is always so helpful. After trying many things here is the conclusion and code is now working perfectly fine I removed the tic toc part time(&start); timer = double(getTickCount()); tic(); It was working but crashing then just to make sure that QImage is not NULL I removed the img = QImage(); // releasing memory with if(!img.isNull()) img = QImage(); Its working perfectly fine now.
    • SOLVED QT image display is not working without declaring openCV namedWindow in windows 10
      General and Desktop • windows 10 c++ qt opencv qt 5.14.2 • • Imran Hassan  

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      @Imran-Hassan said in QT image display is not working without declaring openCV namedWindow in windows 10: The problem is solved great, so please don't forget to mark your post as such!
    • SOLVED Link / Build Error QtCreator 4.10.2, Qt 5.13, OpenCV, Ubuntu 18.04.
      General and Desktop • opencv linking ubuntu 18.04 • • Pl45m4  

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      I still don't know what exactly went wrong, but after I removed all of the OpenCV stuff and re-installed a fresh v4.1, it worked. So even though I checked all lib-files, there must have been something wrong with the linked libs (Pointing to different versions?! Links not working?!, etc.) Thanks @SGaist, your answer made me remove everthing and try the OCV version that is provided by Ubuntu 18.04. I got 3.X.X from there... After I removed this version again (because I want a newer one) and installed 4.1 from OCV page, it worked :-)
    • Create and show the object of my QWidget (heir) in the main window (heir of QMainWindow)
      General and Desktop • qwidget qmainwindow opencv qt designer videocapture • • Algorithm0  

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      @jsulm Hello! Sorry, but that doesn't work. I tried to insert a loop in different places, but the result remains the same. I also tried to display the main widget. @SGaist Hello. So the VideoWindow.h file (VideoWindow class) is my custom widget. This is the first piece of code that I presented.
    • SOLVED QDataStream an openCV::mat serialisation...
      General and Desktop • opencv qbytearray qdatastream • • Dariusz  

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      @jsulm said in QDataStream an openCV::mat serialisation...: @Dariusz What is stream here? Is it QDataStream? "Any idea what did I mess up with this ?" - well, what is not working? Yep :- ) I think I might "got it". Naturally 5 min after asking question... elemSize1() return incorrect number of channels. Looks like I need elemSize() instead. still testing. Yep it was wrong element number. Hope it helps other "serializers" out here : -)
    • SOLVED OpenCV 4.1.1 Imread() & Imwrite() Crashes Program ?
      General and Desktop • opencv imread imwrite • • R-P-H  

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      @r-p-h said in OpenCV 4.1.1 Imread() & Imwrite() Crashes Program ?: now everything is working fine. so please don't forget to mark your post as solved! Thanks.
    • SOLVED Using a label to display large images in QT GUI
      General and Desktop • opengl qlabel opencv image display pixmap • • rtavakko  

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      An update on this. It works perfectly and its a very low-cost solution. My processing time remains almost the same (~10mS) using this method since the painter does the scaling for you when it draws. Thanks for your help guys.
    • UNSOLVED QT 5.12.3, OpenCV 3.4.3, Rasberry Pi 3B+, Cross-Compilation failure
      Installation and Deployment • opencv qt5.12.3 raspberry pi 3b • • Chris1092387456  

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      @chris1092387456 could it be possible you have mixed Qt versions from the one you cross-compiled and the one it's used by the OpenCV install script you used. Assuming you run Ubuntu/opencv_latest.sh which in turn calls opencv_install.sh and then dependencies.sh, there are some apt-get install calls, so you''ll end up having pre-built Qt libraries along with your cross-compiled ones... function install_dependency { echo "--- Installing dependency: $1" sudo apt-get -y install $1 } ... install_dependency libqt5x11extras5 install_dependency libqt5opengl5 install_dependency libqt5opengl5-dev So may I suggest to start from scratch? First I'd follow the mechatronics guide to cross-compile and deploy Qt in the RPi device. Then I'd follow this guide to cross compile the latest version of OpenCV for Raspberry Pi. As you'll use WITH_QT=ON flag I guess, please adjust the paths in the CMake script(s) to use the cross-compiled Qt version in your host PC. And also use the correct path for cross-compiled OpenCV in your .pro file. As example, the following doesn't look good to me: LIBS += -L/usr/local/lib/libopencv_highgui.so
    • UNSOLVED GUI freezing issue
      Mobile and Embedded • qthread gui c++ qt opencv serial interfac • • dev_512  

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      @Gojir4 thanks, I am trying that right now. I’ve added a 1s delay in my image grabbing thread. Let’s see. Fingers crossed!
    • SOLVED OpenCV VideoCapture Failure from QThread
      General and Desktop • qthread gui opencv crash videocapture • • rtavakko  

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      @JKSH This is how I emit the OpenCV mat data: emit processedImage(2, videoFrameOut.ptr(0,0),videoFrameOut.cols, videoFrameOut.rows, videoFrameOut.step); The first parameter is just used to determine which display should draw the image and the rest are dimensions and stride which I think are ok. @SGaist You are correct, I changed the line below to make a copy: displayImage = QImage(imageData, width, height, step, QImage::Format_RGBA8888).copy(0,0,width,height); I think this fixed the issue. I got a couple of crashes in 'memcpy' but that was when loading files a little too quickly. I think most likey resizing the data quickly was the issue. I will do more testing this week and post the results. UPDATE: I did a lot more testing and making a local copy fixed the issue. The issue was that I was modifying the array before it was fully copied and this caused crashes when the array was downsized. I will need to revise the overall structure to make sure everything is done sequentially. Thanks!
    • SOLVED Video Rendering Application with Overlay
      General and Desktop • opencv plot h264 video processin • • cirquit  

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      Thank you for your answer! I've yet to find a good introduction into QML for C++ developers, but I was a little put off by the somewhat convoluted approach as different tutorials either don't show any QML or only use it soley to develop a very simple application. The main problem I'm struggling is with QML is the ability to generate a GUI based on some set preferences. In my case the amount of e.g tabs in the "Options" pane should be defined by the amount of video files which are currently loaded. Is this easily possible to programatically extend QML GUIs?
    • UNSOLVED modeless QDialog passes mouse click event to its parent
      General and Desktop • qwidget qdialog opencv mouse event • • shawnL  

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      Then add a signal to your dialog that you will emit when needed from your mouse move event.
    • UNSOLVED Trouble with #include in Windows
      General and Desktop • opencv include vs2017 • • mdresser  

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      Problem Solved: '/' not '\' in .pro file AND run qmake after change. I tried changing '\' to '/' but didn't run qmake.
    • UNSOLVED How to display image that I already edit with "cv::Line" in Gui?
      General and Desktop • gui opencv draw line • • Mawarditaman  

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      Hi and welcome to devnet, Can you show the code you are using ? What exactly do you expect ? What exactly do you get ?
    • UNSOLVED QWidget: Cannot create a QWidget without QApplication - OpenCV imshow() 2.4.13 ?
      General and Desktop • qwidget opencv qapplication • • R-P-H  

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      @sierdzio said in QWidget: Cannot create a QWidget without QApplication - OpenCV imshow() 2.4.13 ?: Is Qt the only supported backend? If yes, then indeed requirements do propagate. No, it has been added later on. It's maybe even the latest that has been implemented. AFAIK, what the OP is hitting here, is that OpenCV doesn't have an implementation for imgshow for iOS. It would require to either use Qt to show the result of what he's doing or native stuff.
    • UNSOLVED Resizing a constant Video stream from OpenCV to PyQt5 with QPainter in a QWidget using a Raspberry Pi
      Language Bindings • python qwidget qpainter opencv pyqt • • Xenoshell  

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      Yeah i feel like i do sudo apt-get update && upgrade at least once a day. I just checked about SIP and i compiled it from source but i cant remember if i actually used the command make and make install. Does that mean i have to reinstall pyqt5 again? I guess i just open a new thread. Thanks for all the help @SGaist
    • UNSOLVED Unable to read image frames using gstreamer in opencv for yocto linux image
      Mobile and Embedded • linux opencv yocto • • Sumit  

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      Hi, GStreamer in OpenCV ? Shouldn't you rather post this question on either or maybe both of their forum ?
    • UNSOLVED [solved] Astonishingly weird behaviour of Qt Creator + OpenCV
      General and Desktop • qt creator opencv image display • • Gmember  

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      @Chris-Kawa Thank you, now it works. The solution was simple, but apparently I must understand better how the paths work. If you have any advice on where to start reading or you know any interesting online article/tutorial, please tell me :-)
    • UNSOLVED Linking openCv with Qt
      Mobile and Embedded • opencv cpp • • Anas_Deshmukh  

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      Hi, Maybe a silly question but are you sure that OpenCV is properly installed in opencvArm ?
    • SOLVED [solved] Impossible to include OpenCV path
      General and Desktop • qmake opencv includepath • • Gmember  

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      dll paths do not influence the build so they are not included in qmake. if you use QtCreator in the right bar select project and in the build and run tab, select the run subtab and you can customise the run environment adding the paths of the dlls to the run environment PATH otherwise you can use the INSTALLS of qmake to deploy all the binaries where you need them
    • UNSOLVED OpenCV & QT: 'emit' undeclared identifier error
      General and Desktop • qt5 opencv emit signal • • htmlboss  

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      Hi, Just a quick note, taking a look at fixing this "fix", I just saw that the latest version of the contrib repository doesn't contain the offending code anymore.
    • SOLVED Offline mobile based object detection
      Mobile and Embedded • android ios opencv • • Sam_  

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      @Sam_ I'm glad i could help. Please mark the Thread as "solved" if it's solved for you. :)
    • UNSOLVED Display OpenCV Live Cam Feed In Qt
      General and Desktop • c++ opencv qt 5.4.0 • • Trav  

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      hello, here is a working example https://goo.gl/2puvC1
    • SOLVED How to install openCv in Qt
      3rd Party Software • opencv path qt 5.4.0 • • Trav  

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      Good ! In that case, please mark the thread as solved using the "Topic Tool" button so that other forum users may know a solution has been found :)
    • UNSOLVED generate an exe on QT5.2 and OpenCV 3.1 in static mod.
      General and Desktop • opencv static qt5.2 libwebp • • ammarmoez  

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      @SGaist yes all opencv files is included in the path. After some research in log file, i think I have a problème with the génération of libopencv_imgcodecs310 and libopencv_imgproc310 files. I'll keep you posted.
    • SOLVED Can desktop kit in qt for android be used for opencv desktop development
      General and Desktop • opencv qt for windows qt for android • • lama  

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      @SGaist said: Android Hello all, Sorry for the late reply As SGaist said i was able to build and run qt with opencv successfully on windows desktop using mingw for desktop bundled with qt for android Thanks Amal
    • SOLVED OpenCV Error: Unspecified error (The node does not represent a user object (unknown type?))
      Mobile and Embedded • c++ opencv • • sachin786  

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      As it is not related to Qt you should ask OpenCV community.
    • UNSOLVED static opencv build for QT using MinGW. mingw32-make: *** [all] Error 2
      General and Desktop • opencv mingw mingw32-make build from sour • • Griz  

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    • UNSOLVED Is it configuration problem of opencv3.10 with qt 5.5? Showing Error "undefined reference to `cv::imread(cv::String const&, int)"
      Qt in Education • opencv opencv3.10 load imagmatrix sobel • • beginMyCoding  

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      Take a look at the answer here