lobsterman's profile - activity

still hoping someone might point me to an understanding of g_log_structured_standard and similar. compile fails with a n

No, using libreboard renegade (Rockchip RK3328) running lubuntu 18.04. The processor is a quad-core A53x4 64-bit process

compiling OpenCV 4.1.1 on ARM64 hi all, i am hoping someone might be able to get me past this hurdle... i am using a li

i assume that is meant libgtk-3-dev. as i mentioned above i have libgte-3-dev at the newest level from repository (3.22.

continuing to run into the same error. still getting undefined reference to `g_log_structured_standard', now in opencv_a

continuing the to run into the same errors. still getting undefined reference to `g_log_structured_standard' in opencv_a

seeing that it is a problem with opencv_test_core.dir i turned off -DBUILD_TESTS=OFF -DBUILD_EXAMPLES=OFF -DBUILD_op

seeing that it is a problem with opencv_test_core.dir i turned off -DBUILD_TESTS=OFF -DBUILD_EXAMPLES=OFF -DBUILD_op

thanks supra56, but "make -j4" and using OpenCV 4.2.0 gives the same result ... /usr/lib/aarch64-linux-gnu/libgtk-3.so:

compiling OpenCV 4.1.1 on ARM64 hi all, i am hoping someone might be able to get me past this hurdle... i am using a li

compiling OpenCV 4.1.1 on ARM64 hi all, i am hoping someone might be able to get me past this hurdle... i am using a li

Imgproc.undistort() seems missing in OpenCV4 Java video app uses Imgproc.undistort(frameIn,frameout_undist,cameraMatrix

I am calling VideoCapture.open(0) and everything works like a charm if I have a device at ID 0. Problem is if I don't have a openable device there, OpenCV will continue trying to establish a connection afaik - FOREVER. This occurs for example when I run the code on my laptop which has a facetime HD camera in the lid. if i run the computer from an external monitor and I have the lid down then it just hangs forever. As soon as I open the lid it springs to life. Is there any way to specify a timeout for trying? If it will never stop trying to connect then constructs like ...

if (!cap.isOpened()) // check if we succeeded

make no sense, because it will never report that it did not succeed. any solutions? I am using OpenCV 2.4.10 on Mac OSX 10.10 with Java 1.8.0_25. Thanks,

i am answering my own question in case someone else gets here with a similar problem. i had tried to install opencv first with homebrew, then ran into issues and switched to macports. had to go back into homebrew and first uninstall ffmpeg, then start over and install opencv in macports ... voila, and all worked like a charm

thanks a stack. sorry, put it into title that i needed to grab from 8U1 image. just tried this and grabbing to whole byte array and iterating through that really makes this fly. iterating through pixel by pixel with get takes 10ms for a hd frame, grabbing all in one bunch and then reading from bytes[] takes .... wait for it ... 0.1ms. thanks a major stack berak

i already have the grayscale image (CV_8U1), that is why i need to get the value of single bytes per pixel. the question is about what the fastest way is to get that pixel value.

I am hoping to squeeze every ounce of speed from opencv videocapture. Can someone please enlighten me as to whether there is a better method to access individual pixel grayscale values as i iterate through a CV_8U1. i am using currently

public int getValue (int Col, int Row) { 
    return (int)itsMat.get(Row,Col)[0];
}

all help greatly appreciated.

thanks, doombot, yeah, in my app grayscale is sufficient and i am getting 22fps at 1280x720 which is quite ok, but i would like to progress towards the camera's max of 60fps in asynchronous mode. for that my ability will yet need to improve towards reading frames in grayscale directly as CV_8U1 rather than to capture in 3 channels in CV_8U3 and reducing it in a later step. it would be greatly appreciated if anyone has any insights on how opencv specifically interfaces with the camera and what of that functionality is accessible to me in java.

thanks a stack for the answer. right now i am still learning the basic opencv framework and i am using the build-in facetime HD camera for that, not sure whether this one offers yuv. the camera i will try to interface for the real need for speed in grayscale processing is the elphel open source design type camera (elphel 353) <www3.elphel.com/model_353_cameras>. the elphel does seem to offer a bunch of formats but i am not sure how to make opencv talk to it with the right settings, i know i can pull out rgb and convert, but if there is any way to specifically pull out the Y channel of YUV, or if i can just read frames in grayscale, then this puppy would be seriously cooking. asynchronous access would be sweet too. for code i get the frames as Mat with videocapture.read()

hi all, i am trying to get every ounce of speed from my opencv/java videocapture. System works like a charm, but i think i am still wasting clock cycles ...

Currently i read color frames from videocapture device into Mat, update the content of a BufferedImage via arraycopy, then repaint into jpanel. at 1280x720 i get around 20fps with fairly old Mac Powerbook hardware, which is not bad. In my application, grayscale is actually good enough. i know how to change the color frame to a grayscale one using

Imgproc.cvtColor(MatImg, MatImg_mod, Imgproc.COLOR_RGB2GRAY);

but that gains me nothing for speed. Anyone know of a way to already pull frames off the camera in grayscale? or to do the Y channel only in the YUV route? any suggestions for how to squeeze some speed out of this puppy and any code examples greatly appreciated. thanks,

hi all, i am struggling to get the getSupportedPreviewSizes() function to work in opencv 2.4.10/Java1.8.0_25/eclipse luna/osx 10.10. i am able to talk to the camera in my powerbook without problem and i pull off frames at Width 1280 Height 720. But when it gets to line List<size> aList = camera.getSupportedPreviewSizes(); the app just hangs and then terminates without reporting an exception. any suggestions? anybody ever got the function to work in java? thanks a stack,

Mat frame = new Mat(); 
VideoCapture camera = new VideoCapture(0);
if (camera.isOpened()) {
    System.out.println("Camera opened");
    if (camera.read(frame) && !frame.empty()) {
        System.out.println("Width " + frame.width() + " Height " + frame.height());
    }
    List<Size> aList = camera.getSupportedPreviewSizes();
    for (Size s : aList) {
        System.out.println(s);
    }
}

Hi all, I am attempting a compile of opencv-2.4.9 unix on mac osx 10.9.2. downloaded from sourceforge, it stops when it hits the maximum of these booboos

/Users/rhuber/Documents/C-Java/opencv/opencv-2.4.9/modules/highgui/src/ffmpeg_codecs.hpp:126:7: error: 
      use of undeclared identifier 'CODEC_ID_MPEG4'; did you mean
      'AV_CODEC_ID_MPEG4'?
    { CODEC_ID_MPEG4, MKTAG(0x04, 0, 0, 0) }, /* some broken avi use this */
      ^~~~~~~~~~~~~~
      AV_CODEC_ID_MPEG4
/usr/local/include/libavcodec/avcodec.h:123:5: note: 'AV_CODEC_ID_MPEG4'
      declared here
    AV_CODEC_ID_MPEG4,
    ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]

the same problem occurs when i go back to the earlier versions OpenCV-2.4.3 and opencv-2.4.6.1. i am thinking it is somehow related to having a version of ffmpeg installed somewhere that is either too new or too old for opencv. any suggestions on how i can fix it?