Face Recognition In One Minute

We were inspired for this work by the following reference:

Online Semi-Supervised Perception: Real-Time Learning without Explicit Feedback, Branislav Kveton, Michal Valko, Mathai Phillipose, Ling Huang, 2010

Installation

NB: repo contains lot of imgs... 5 required files are in the following list + 1 data set of images with faces:

Download:

• LFW-funneled (13000 imgs) http://vis-www.cs.umass.edu/lfw/ (but you can use any dataset with imgs of people as long as it is diverse enough >1000)
• py folder from this repository
• cascade folder from this repository
• requirements.txt

On Mac OS / UNIX:

sudo apt install virtualenv # if not already installed
mkdir face_reco
cd face_reco
virtualenv -p python3 face_reco_env
source face_reco_env/bin/activate
pip3 install -r requirements.txt
# change variable PWD to current path of folder at the top of main.py and realtime_graph_of_faces.py
python3 main.py

Interest of the method

Our philosophy during this work was to be able to work in real-time fashion. Therefore to avoid any heavy computation or training time. In some sense we wanted to produce a low-cost method of face recognition. In addition to the fact that only light computation is performed, it does not require any prior domain knowledge and it is little demanding on data. It only requires a dataset of raw 1000 imgs with people on them without any label required. We used LFW-funneled dataset available online for free which provides 13000 images. An other strong interest is the possibility to improve model by simply adding unlabelled imgs (hence semi-supervised) to graph. That's what we used at boosting step with success. Also authors Branislav Kveton et al. claimed to obtain results using harmonic solution which are better than using KNN method.

Thus we used a pre-trained Viola-Jones algorithm Robust Real-time Object Detection, Paul Viola , Michael Jones, 2001 which has been thought to be fast and small device friendly.

We also used PcaNet model which has a low amount of parameters (roughly 200) and is very fast to learn and yet produces good results (cf https://github.com/salimandre/PcaNet).

To produce inference over new face imgs we need to compute one row of similarity matrix per unlabelled img then compute an harmonic extension of a function over the graph of faces. This takes basically O(|V|^3) for one frame.

Our Pipeline

inputs:

• pre-trained Viola-Jones algorithm
• a dataset of 1000 imgs from different people

step 1: take few snapshots in real-time of you, varying your pose and your distance to webcam

These imgs will be added to Graph Of Faces and labelled as true.

step 2: search of best Graph Of Faces.

• repeat a certain amount of times:

  • Sample Images from LFW-funneled dataset

  • 

  • Extract faces compute bounding boxes using Viola-Jones algorithms to detect faces on every imgs.

  Perform preprocessing step: crop, convert to grayscale, resize.

  • 

  • Add nodes to graph Faces from LFW-Funneled will be labelled as false while faces from snapshots as true

  • 

  • Train PcaNet on current true/false face images.

  • Inference of features on faces

  • Evaluate Graph Of Faces + PcaNet model

    • repeat 100 times:

      • sample randomly an image from dataset:

      • compute one row of similarity matrix using L1 distance

      • 

      • 

      • solve the following optimization problem:

      • 

      • by producing the harmonic solution:

      • 

      • compute the % of false positive

• Take best model with lowest false positive rate

step 3: Perform Boosting step by randomly choosing faces from dataset which are barely classified as False by Graph Of Faces model. These nodes should be referred as boosting nodes or support nodes.

step 4: Perform inference using boosting on frame.

For each frame perform "all in one" inference for both current frame and for faces chosen at previous step.

Results

We used the following settings:

step 1: we took 7 snapshots

step 2: we sampled graph of faces/PcaNet 10 times to find 5 imgs of stars + best PcaNet. Model was evaluated on 100 random imgs from LFW-funneled dataset.

step 3: we added 40 support nodes among 500 random imgs.

Running time: Snapshots took 14s (1 every 2s) + 1:09 of computations

Evaluation We tried many runs and we evaluated the false positive rate on 1000 random imgs from LFW-funneled and we obtained 0.01%. If diverse poses are taken during snapshots then recognition is robust to face movements as long as Viola-Jones detect a face. Although we lacked of evaluation in real condition with many different people taking diverse poses.

Limits

• Viola-Jones detection method does not capture well changes of pose therefore to detect a face we need it to be mostly frontal

• we do not use a pre-trained segmentation tool to extract faces from background in bounding boxes.

• We resised imgs to (50,37) for PcaNet in order to limit the number of features to 1920 (with our own current version of PcaNet we lack of flexibility) but with an other model (MobileNet?) it may be possible to use bigger imgs and have same quality of features or even better.

• Sensible to illumination