OpenCV integration

[pherthyl]

Thanks for code!
I'm running example and capture frame size isn't changing, it seems to me that cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH, 640); does nothing. Or have I missed something?

if(size == Size640) {
cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH, 640);
cvSetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT, 480);
qDebug() << "Setting 640x480:CV_CAP_PROP_FRAME_WIDTH:" << cvGetCaptureProperty(capture, CV_CAP_PROP_FRAME_WIDTH);
qDebug() << "Setting 640x480CV_CAP_PROP_FRAME_HEIGHT:" << cvGetCaptureProperty(capture, CV_CAP_PROP_FRAME_HEIGHT);

}

returns:
Setting 640x480:CV_CAP_PROP_FRAME_WIDTH: 320
Setting 640x480CV_CAP_PROP_FRAME_HEIGHT: 240

Any ideas how could I change frame width/height?
Best regards,
Milan

No. This is what I was talking about when I said the highgui functions suck

On some cameras those functions will work, but on most they won't. If you want to control camera properties like capture size and others you'll have to use another image acquisition library or try cvcam as someone else suggested. I never had much luck with it. It'll do basic capture, but that's it.

[kosirm]

thanks...

best regards, Milan

[switch]

Sorry to re-awaken an old topic but i am having some difficulties converting an opencv Monochrome image into a Qimage. The image is a result of calling the opencv function
void cvInRangeS( const CvArr* src, CvScalar lower, CvScalar upper, CvArr* dst );

When i pass this image to the function IplImageToQImage it does convert the image into qimage however the image is 8 times smaller and duplicated. The results can be seen below

Opencv Image


Convertion to Qimage results



Does anybody know why this has happened? And any ideas how to correct the error?

[pherthyl]

Not sure why you're getting that. Have you tried looking at the dst image before you convert it to a QImage (using the highgui showimg function)? Make sure the dst image is the correct bit depth (8u or 8s).

[eumesmo]

Hello pherthyl,


Thanks for the framework, it's very good, but I found a problem running in my hardware. I tested the framework in a Hp notebook, with the webcam and with a external camera and worked fine. When a tried the framework in another notebook (a LG note) with the integrate webcam, a get an deadlock every time I stop and try a play again.

The console output: (this problem in this notebook occurs every time, it's not a random problem...)


Listing capture properties...
CV_CAP_PROP_FRAME_WIDTH
CV_CAP_PROP_FRAME_HEIGHT
CV_CAP_PROP__FPS 0
CV_CAP_PROP_FOURCC 0
CV_CAP_PROP_BRIGHTNESS 0
CV_CAP_PROP_CONTRAST 0
CV_CAP_PROP_SATURATION 0
CV_CAP_PROP_HUE 0
Done
Setting 640x480 1
Attempting to set frame rate...
Error: 0
Starting to track
About to start the capture thread
Started the capture thread
Stop capture requested.
Waiting on capture start...
Listing capture properties...
CV_CAP_PROP_FRAME_WIDTH
CV_CAP_PROP_FRAME_HEIGHT
CV_CAP_PROP__FPS 0
CV_CAP_PROP_FOURCC 0
CV_CAP_PROP_BRIGHTNESS 0
CV_CAP_PROP_CONTRAST 0
CV_CAP_PROP_SATURATION 0
CV_CAP_PROP_HUE 0
Done
Setting 640x480 1
Attempting to set frame rate...
Error: 0
Starting to track
About to start the capture thread
Started the capture thread
QMutex::lock Deadlock detected in thread 3916



Well, another test that I did, it's to start a HeadTracker object when a button is pressed in the main window. Well, it works fine until I request a re-size. After a re-size the program crashes and close.


It's just a report, but any help it's very welcome, I will have a better lock in the code to see if I can improve anything, because I think is a very good framework and really fast as well

cheers!

[mounte]

I know this thread is quite old, but still it is a very good wrapper to get images from webcam or whatnot.

If for some reason you dont need some fancy 32 bit format you could change the updatePixmap function to only use one memcpy like this:

QTime t;
    t.start();
    //qDebug() << "Copying data";
    bool start = false;
    // check if the frame dimensions have changed
    if(frame->width != imageWidth || frame->height != imageHeight) {
        if(imageData) {
            delete[] imageData;
        }
        start = true;
        imageWidth = frame->width;
        imageHeight = frame->height;
        emit(frameSizeChanged(imageWidth, imageHeight));
        imageData = new unsigned char[3*imageWidth*imageHeight];
    }
 
    int pixels = imageWidth * imageHeight;
    uchar* src = (uchar*)(frame->imageData);
 
    memcpy(imageData, src, pixels*3);
    if(!start) {
        ++frames;
        time += t.elapsed();
    }

QTime t;
    t.start();
    //qDebug() << "Copying data";
    bool start = false;
    // check if the frame dimensions have changed
    if(frame->width != imageWidth || frame->height != imageHeight) {
        if(imageData) {
            delete[] imageData;
        }
        start = true;
        imageWidth = frame->width;
        imageHeight = frame->height;
        emit(frameSizeChanged(imageWidth, imageHeight));
        imageData = new unsigned char[3*imageWidth*imageHeight];
    }

    int pixels = imageWidth * imageHeight;
    uchar* src = (uchar*)(frame->imageData);

    memcpy(imageData, src, pixels*3);
    if(!start) {
        ++frames;
        time += t.elapsed();
    }

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Then you have to change the paintEvent method to create the tImg with RGB888 format like this:

QImage tImg(imageData, imageWidth, imageHeight, QImage::Format_RGB888);

QImage tImg(imageData, imageWidth, imageHeight, QImage::Format_RGB888);

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You might run into problem of RGB <--> BGR conversion, just modify the painter.drawImage call to

painter.drawImage(QPoint(0,0), tImg.rgbSwapped());

painter.drawImage(QPoint(0,0), tImg.rgbSwapped());

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