Run target detection, import CV2   Normal, CV2. Write() is OK, but CV2. Imshow() has an error: function not implemented, prompting windows and Ubuntu to install libgtk2.0-dev and PKG config, re run cmake

PIP install opencv Python runs unresponsive.

Recall that Anaconda was installed later and uninstalled first. Sure enough, the original opencv relied on Python 3.8 of Ubuntu 20.04.

uninstall  After installation, reinstall install and everything is normal.