Opencv trackbar crash when I slide

[berak]

@rap

The opencv version is 4.2 and I install on Ubuntu 20.4 with de package : sudo apt install libopencv-dev

that’s terribly old

@rap

    int lowHue =0
    int lowSaturation = 0
    int lowValue = 0
    int highHue = 255;

hmm, those are local variables (inside the constructor) ?
if so, the address you pass to createTrackbar()
will be invalid later (“dangling pointer”)
once you move the trackbar, it will try to write the current value back to this address, aand it goes kaboom.

rather use a pattern like:

cv::createTrackbar("Low hue","Configuration", NULL, 255, OnChangeLowHue, this);
cv::setTrackbarPos("Low hue","Configuration", lowHue);