If you’re sure that the value of img is None in your case, you can simply use if not img is None, or, equivalently, if img is not None. You don’t need to check the type explicitly. Note that None and False are not the same value. However, bool(None)==False, which is why if None fails. … Read more
It seems you already have imported the opencv module, now, open your CMakeList.txt and add the follow lines: set(CMAKE_VERBOSE_MAKEFILE on) add_library(lib_opencv SHARED IMPORTED) set_target_properties(lib_opencv PROPERTIES IMPORTED_LOCATION path-to-your-project/MyApplication/app/src/main/jniLibs/${ANDROID_ABI}/libopencv_java3.so) include_directories(path-to-opencv-directory/OpenCV-android-sdk/sdk/native/jni/include) set(CMAKE_CXX_FLAGS “${CMAKE_CXX_FLAGS} -std=gnu++11”) and edit the: target_link_libraries( # Specifies the target library. native-lib lib_opencv # Links the target library to the log library # included in the … Read more
I described some tips for preparing images for Tesseract here: Using tesseract to recognize license plates In your example, there are several things going on… You need to get the text to be black and the rest of the image white (not the reverse). That’s what character recognition is tuned on. Grayscale is ok, as … Read more
It’s all because OpenCV uses Automatic Memory Management. OpenCV handles all the memory automatically. First of all, std::vector, Mat, and other data structures used by the functions and methods have destructors that deallocate the underlying memory buffers when needed. This means that the destructors do not always deallocate the buffers as in case of Mat. … Read more
A lot of your questions stem from the fact that you’re not sure how morphological image processing works, but we can put your doubts to rest. You can interpret the structuring element as the “base shape” to compare to. 1 in the structuring element corresponds to a pixel that you want to look at in … Read more
First, check out /samples/c/squares.c in your OpenCV distribution. This example provides a square detector, and it should be a pretty good start on how to detect corner-like features. Then, take a look at OpenCV’s feature-oriented functions like cvCornerHarris() and cvGoodFeaturesToTrack(). The above methods can return many corner-like features – most will not be the “true … Read more
From your question I guess you are using Ubuntu (or a derivate). If you use: apt-file search opencv.pc then you see that you have to install libopencv-dev. After you do so, pkg-config –cflags opencv and pkg-config –libs opencv should work as expected.
Yes OpenCV is more robust and flexible and can perform most of the image processing routines which are available out there, So probably this filter can be done with OpenCV> However, there may not be a straightforward API for that. Anyways, as far as the conversion of image format from OpenCV to PIL is concerned … Read more
For version 2.0, you must build the project from source. Here’s what you will need: The OpenCV installer. CMake. Here’s the CMake installer. Instructions for using CMake to install OpenCV-2.0.01-win32. Those instructions need an extra step if you are using a vc++ Express edition. In that case you must un-check ENABLE_OPENMP when running the CMake … Read more
Before using OpenCV’s Gstreamer API, we need a working pipeline using the Gstreamer command line tool. Sender: The OP is using JPEG encoding, so this pipeline will be using the same encoding. gst-launch-1.0 -v v4l2src \ ! video/x-raw,format=YUY2,width=640,height=480 \ ! jpegenc \ ! rtpjpegpay \ ! udpsink host=127.0.0.1 port=5000 Receiver: The sink caps for rtpjpegdepay … Read more