Mostly Java/Scala OpenCV resources but there are some tutorials for other languages/frameworks, if they do a good job explaining things.

Reading material

What is the best face detector model?

Description of the three available face recognizers in OpenCV. (Not SFace).

How LBPH recognition works

Face recognition with OpenCV

Setup

FIRST OF ALL - here is a crash course for how OpenCV, JavaCV, JavaCPP dependencies are related, and how to build it for each platform.

• Platform-specific setup using sbt-javacpp presets. Also a very good example of Akka stream processing (advanced stuff here):

  https://github.com/duanebester/streaming-ocr

• Another, slightly different way to do the above:

  https://github.com/pupudu/javacv-examples/blob/master/OpenCV2_Cookbook/build.sbt

• The JavaCV SBT plugin - here specifically explains how to build for other platforms

  https://github.com/bytedeco/sbt-javacv

• JavaCV - what JavaCV SBT wraps, also has manual JAR install instructions

  https://github.com/bytedeco/javacv

Face detection

DeepNet

• OpenCV cookbook example

  Ex1FaceDetection.scala

• DNN detection question and tutorial (Haar has awful results):

  https://stackoverflow.com/questions/63122406/face-recognition-does-not-detect-any-with-opencv https://learnopencv.com/face-detection-opencv-dlib-and-deep-learning-c-python/ https://towardsdatascience.com/face-detection-models-which-to-use-and-why-d263e82c302c

• TUTORIAL: Face detection pipeline with Akka

  https://beachape.com/blog/2016/03/14/scala-and-opencv-ep-2-akka-face-detector/

Haar Cascade (do not use, for reference only)

• OpenCV classifier data for Haar cascade classifier:

  https://github.com/opencv/opencv/tree/master/data/haarcascades

• A very simple method to detect a face with a classifier and draw a bounding rectangle around it (2016)

  https://github.com/PhilAndrew/scalaopencv...

• Ancient face detection code, says "Scala" but the project is Java. (2013)

  https://github.com/vspiewak/opencv-scala-sample/blob/master/src/main/java/FaceDetector.java

• TUTORIAL: Facial Recognition Using OpenCV In Java: A Developer‘s Guide

• TUTORIAL: Image Processing in Java – Face Detection

• ExoVisix - Advanced example with multiple classifiers and video frame grabbers:

  https://github.com/anupsarkar-dev/ExoVisix/blob/master/src/application/FaceDetector.java

RetinaFace

Supposed to be THE best open-source model.

Output is here - particularly the 10x landmark matrix that we MIGHT be able to use with SFACE align and crop.

https://docs.openvino.ai/archive/2021.3/omz_models_model_retinaface_resnet50.html

Original question and code is here: https://stackoverflow.com/questions/76497427/javacv-dnn-retinaface-model-how-to-get-the-face-and-landmark-information

Caffemodel: https://github.com/cholihao/Retinaface-caffe/tree/master/caffemodel

Face recognition

• A recognition service from an ML course - DNN and embeddings:

  https://github.com/iproduct/course-ml/blob/main/10-ml-h2o/src/main/java/org/iproduct/ml/h2o/opencv/FaceRecognition.java

• "The solution is very inefficient in its current form as the training model is built at each run, however it shows what's needed to make it work." (2019)

  OpenCVFaceRecognizer

• Recognizer class with the match() function for feature comparisons (detect similar faces)

  https://docs.opencv.org/4.x/javadoc/org/opencv/objdetect/FaceRecognizerSF.html

  The C++ version of usage is here

  ❗ ❗ ❗ Example of a much better and practical YUNET/SF detection/comparison

  isFaceSimilar()

  Java version of comparing faces but using any recognizer example

• Android example with face recognition and pretty involving face-matching:

  https://github.com/thfhongfeng/AndroidAppTemplate/blob/master/lib_face_dr/src/main/java/com/pine/app/lib/face/matcher/opencv/algorithm/SFMatchAlgorithm.java

• ExoVisix example (see detection example above)

  https://github.com/anupsarkar-dev/ExoVisix/blob/master/src/application/FaceRecognizer.java

• An approach to unsupervised clustering of unknown faces:

  https://bitsearch.blogspot.com/2013/02/unsupervised-face-clustering-with-opencv.html

All-together tutorials

• C# - a very impressive runnable and online demo of face detection/recognition:

  https://facerec.gjung.com/FaceDetection

• (Python) - Detect, embed, recognize with OpenCV: https://pyimagesearch.com/2018/09/24/opencv-face-recognition/

Similarity search

• A very good StackOverflow response, describing methods, with code examples:

• OpenCV Template search docs

• DiskANN library https://github.com/microsoft/DiskANN

• Nearest-neighbor vector search - Facebook FIASS

Object detection / other

• YOLO https://opencv-tutorial.readthedocs.io/en/latest/yolo/yolo.html

• Object detection tutorial for Java/Android https://docs.opencv.org/3.4/d0/d6c/tutorial_dnn_android.html