Masked Facial Recognition

2020/2021 HKUST CSE FYP Masked Facial Recognition, developer: Sam Yuen, Alan Xie, Tony Cheng

Supervisor: Prof. Dit-Yan YEUNG

This Github repository shows how to train a masked face recognition model. We use the masked facial recognition models to build a building security system in another Github repository.

Download masked facial recognition train and test data

We use a tool call MaskTheFace to simulate masked facial images based on some famous face image datasets. We choose several different masks to simulate. They are green surgical mask (#44b4a8), blue surgical mask (#1ca0f4), white N95 mask (#FFFFFF), white KN-95 mask and black cloth mask (#000000).

Preview of part of the data:

train_data

Figure 1. Some training data of CASIA after preprocessing

image_pair

Figure 2. Some image pairs of Evaluation and testing sets, the upper two pairs are same person, the bottom two pairs are different people

Dataset	# Identities	# Images
CASIA	10,585	492,832
VGG2	8,631	2,024,897
LFW (eval+test)	5,749	64,811

Information of all datasets shown above is after preprocessing so the numbers and sizes differ from the original datasets

Training set 1 (Masked CASIA) 3GB Link: Google Drive
Training set 2 (Masked VGG2) 11GB Link: Google Drive
Training CSV (Masked CASIA + Masked VGG2) 115MB Link: Google Drive
Test set (LFW), including evaluation set and test set, 148MB Link: Google Drive
Evaluation set 1 CSV (all same person pairs) 7MB Link: Google Drive
Evaluation set 2 CSV (all different person pairs) 7MB Link: Google Drive
Test CSV, 782KB Link: Google Drive
Real faces, 81MB Link: Google Drive

There are totally 75 real people in this real face dataset, every class has 3 no masked and masked images seperately. Some of than has higher resolution and has not been cropped and aligned by MTCNN. It is becuase we use this data on our recognition system to simulate users' registration.

Most of them are politicans or celebrities. Some of the real faces are from MRF2, some of them are collected by us from Google.

Download Pre-train models

Models	# Architect	# Loss func	# Pre-trained	# Acc
Model1	InceptionResNetV1	ArcFace with focal loss	Yes	95.xx%
Model2	InceptionResNetV1	Triplet loss with online triplet mining	Yes	94.xx%
Model3	SE-ResNeXt-101	ArcFace with focal loss	No	93.xx%

You may train a model with better performance than ours because we are dealing with our fyp in limited time. You can feel free to fine tune the hyperparameters or deal with any other approaches with our resources.

Model1 (148MB) Link: Google Drive

(Please be careful that model 2 and its optimizer are combined in this .pth format rather than .pt format)

Model2 (290MB, including model and optimizer) Link: Google Drive

Model3 (229MB) Link: Google Drive

To load the model 2, you need to use this function becuase this model was trained by another groupmate:

def load(name, model, optimizer):
    checkpoint = torch.load('../Model/' + name)
    model.load_state_dict(checkpoint['model_state_dict'])
    optimizer.load_state_dict(checkpoint['optimizer_state_dict'])
    for state in optimizer.state.values():
        for k, v in state.items():
            if isinstance(v, torch.Tensor):
                state[k] = v.cuda()

If you want to know more about the training process and concept, you can read our progress report, final report and the following papers:

You can find more in the reference list.

Run

Before you run you need to install the follow package or library first:

pip install tqdm

pip install facenet-pytorch

pip install efficientnet

pip install timm

We expect that you have install other common packages like torch, numpy, pandas...

Create folders call models and result under this directory to save the models and eval images during training or change the directory in the script (train.py).

To train a model with online triplet mining, run:

python3 main.py

To train a model with ArcFace, run:

python3 main2.py

Methodolegy

Figure 3. Architects for Triplet loss and ArcFace Triplet Figure 4. A simple method for triplet loss but this might suffer from model collapse Figure 5. Online triplet mining method, the more popular one for triplet mining.

To know more our training methods in details, please read our progress report and the paper in reference.

Result

In our experiment, we observe that Arcface's performance is slightly better than online triplet mining and also the training time per epoch is shorter than online triplet mining. It is becuase online triplet mining need to sample mini batch to calculate the hardest/semi-hard triplet loss. We only show the result of the model 1 (Pre-trained InceptionResNetV1 with Arcface here)

Train result

In the paper Masked Face Recognition for Secure Authentication, they mentioned that they tried online triplet mining and train the InceptionResNetV1 without pre-trained. We also followed the same method to train a model, but the result is not that good as the one shown in their paper. In our experiment with online triplet mining, the model was difficult to converge and it is very sensitive to how you select the triplet pairs e.g. hardest triplets or semi-hard triplets. Then, arcface is much easier to be controlled compared with online triplet mining.

Training loss: Since we use pre-trained model, the loss reduces and converges more easier than without transfer learning. Without pre-trained, the model needs to be trained with more epochs (around 60 - 120 epochs) compared to 20 - 30 epochs with pre-trained model. We also use multi-step lr decay scheduler to reduce the learning rate. At the beginning, the learning rate is 0.1. The lr will decay 0.1 after epoch 5, 10, 15 and 20.

train_loss Figure 6. Training loss with learning rate decay

We also tried SE-ResNeXt-101 and EffectiveNetB2 to B4. The two models only have the pre-trained version on ImageNet. It is not suitable for transfer learning on face recognition. However, we also did experiment on their pre-trained version and starting from scratch. The result is that there may result collaspe in the model very easily which was not only happened with triplet loss but also arcface sometimes. EfficientNet is usually more likely to result in model collapse after few training epochs.

model_collapse

Figure7. Model Collapse of EfficientNet B4

Evaluation method

Eval graph: The L2 distance of the embeddings of the image pairs. We will calculate and plot this graph at the end of each epoch.

distribution Figure 8. Eval graph

IOU: We plot the eval graph at the end of each epoch. IOU = area of the intersection / area of the eval graph

IOU Figure 9. IOU

The model with lowest IOU will be saved as the best model.

Test result

We use 6,482 pairs of images to be the test set, half of the pairs are the same person and the another half is different people.

Label 0 means that the pair is from two different people and label 1 means that they are from the same person.

This result is from the model1 InceptionResnetV1 with ArcFace. The accuracy is almost 96%.

The test result matches the eval result. As you can see, more pairs of same person are classified incorrectly.

Test Result Figure 10. Confusion matrix

Evaluation matrix:

Accuracy: 0.9585004628201172

              precision    recall  f1-score   support

           0       0.93      0.99      0.96      3241
           1       0.99      0.93      0.96      3241

    accuracy                           0.96      6482
   macro avg       0.96      0.96      0.96      6482
weighted avg       0.96      0.96      0.96      6482

Please be careful that the face recognition test performance here may be different from a face recognition system. It is becuase face recognition system needs more technical approaches rather then a CNN model with threshold only.

What you can improve through our resources

Try fix the problem of model collapse in EfficientNet. If you have sufficient computational power, you can try EfficientNet B7. We used a workstation with 4 RTX2080 Ti 11GB GPUs, but the cuda does not have enough memory when we try EfficientNet B7. We believe that EfficientNet is much more powerful than InceptionResNetV1 according to Google's paper.
Compare Online triplet mining and arcface again, we did not perform too much experiment on them becuase of limited FYP period.
Try to sample a more balancing dataset based on our training set, this means that each class have same number of images.
Fine tune the hyperparameters
Try more new techniques
Use real masked facial images to train, rather than using simulated masked images. (This is quite difficult, we can only wait some research team like VGG from U of Oxford to collect a large real masked facial images)

Masked facial recognition is not that difficult or impossible. The most difficult part is that how to achieve a performance as good as normal facial recognition (>99% accuracy). Also, the most time consuming part / difficult part is not machine learning techniques/approaches here. It is how to collect a suitable training dataset with enough data. You can find some papers about this topic quite easily, but it is not easy to find suitable datasets/code. That why we open-source our pre-processed training data to everyone.

Reference list

Only show some important reference:

License

MIT license is used here. You can follow the permission to do whatever you want. However, some of our code is from other developers, you should be careful that some of them may be prohibited from commerical use.

Contact

Please feel free to push your changes to improve the code here. If you have any problems, you could contact us through samyuan101234@gmail.com

SamYuen101234 / Masked_Face_Recognition

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