SOD neural network library implimentation on Arduino for object detection.
compiles for arduino due currently.
was going to try sobel kernel face detection for faster results but this seems to be plenty fast.
Markov random field might be a fast option for facedection.
ImageSets to download BioID-FaceDatabase-V1.2 http://www.vision.caltech.edu/Image_Datasets/
Licence Dual Licence GPL/Commercial https://pixlab.io/sod https://github.com/symisc/sod based on this library
https://github.com/espressif/esp-face here is another one, the trainer seems to be closed source though.