Facial element detectors based on the Viola and Jones general object detector
xml files for OpenCV designed for different face related elements.
Detectors include as target head and shoulders, eye, ears, mouth and nose detection. Most of them were distributed whithin OpenCV before release 3
A couple of python sample codes are included, revised for python 3.7 opencv 4.1.1
Observe the license details included in each xml file.
If any of these detectors helps you to reduce time to develop, donations are welcome :)