this section, analyzes the combination of existing conventional methods of FR for SFAS based on various comparative analysis results. In actual scenarios, the scalability structure in a distributed environment for an authentication system is achieved based on facial feature extraction and FDR methods, which are often accompanied by substantial calculation [13] [14]. Two embedded platforms (Raspberry Pi on the end-user side and a standard computer on the server side) serve as distributed environment platforms to improve the easy process of facial feature extraction and FDR tasks. In the experiments, the FERET dataset [20], that contains 11,338 face images with an image size of 512x768 pixels captured with 13 poses. The specifications of the embedded platform hardware are as follows:
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Raspberry Pi on the side of the end-user-access with Broadcom BCM2711, Quad-core Cortex-A72 (ARM v8) 64-bit SoC @ 1.5GHz, 8GB LPDDR4-3200 SDRAM, and 2.4 and 5.0 GHz IEEE 802.11ac wireless, Bluetooth 5.0, BLE gigabit Ethernet.
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A standard computer used as a server: AMD Ryzen 5 2600, 6-core processor with NVIDIA GeForce GTX 1650 GPU with VS code, WSL, and TensorFlow-GPU = = 1.15 installed.
Facial feature extraction is crucial stage in this paper, because we address FDR to realize scalability in the distributed environment. Choosing a feature descriptor that helps determine the robustness and performance of scalability for authenticated systems is critical. We consider feature descriptors, such as the Gabor filter, LBP, HOG and DCNN. To evaluate the effectiveness and efficiency of the feature descriptors, we also considered the FR accuracy by comparing the results of various classifiers such as the SVM, k nearest neighbor and artificial neural network. From the classification stage, the authentication is validated for the end-user access through the adopted classifier that trains and tests extracted features to validate each detected end-user face in the corresponding dataset. The performance of feature descriptors in terms of accuracy and processing time with various classifiers is presented in Tables 1 and 2.
Table 1
Recognition-accuracy feature descriptors performance of classifiers by authentication system user access
Feature descriptors
|
Classifier-Processing time (ms)
|
SVM
|
k-NN
|
ANN
|
Gabor filter
|
302
|
410
|
290
|
HOG
|
431
|
503
|
378
|
LBP
|
387
|
479
|
281
|
DCNN
|
178
|
237
|
238
|
Table 2
Processing-time feature descriptors performance of classifiers by authentication system user access.
Feature descriptors
|
Classifier-Processing time (ms)
|
SVM
|
k-NN
|
ANN
|
Gabor filter
|
302
|
410
|
290
|
HOG
|
431
|
503
|
378
|
LBP
|
387
|
479
|
281
|
DCNN
|
178
|
237
|
238
|
We evaluate the feature descriptor performance based on recognition accuracy and processing time. By analyzing the comparative results of the presented feature descriptors with various classifiers on the FERET dataset, the combination of the DCNN and SVM algorithm display promising results with the highest authentication accuracy compared to other feature descriptors and classification algorithms.
Furthermore, we compared the results of various FDR methods such as PCA, LDA and SVD. To gain more insights into the FDR performance of the proposed method, we conducted experiments by applying various dimension reduction algorithms to the extracted facial features with dimension reduction scales of 10%, 20%, 30%, 40% and 50%, the performance results are provided in Fig. 7.
Based on the presented experimental results in Fig. 10, the combination of the DCNN with PCA can be adopted for a scalability approach in the distributed environment. Thus, this method inherits properties of the scalability approach. For example, features are extracted from the original face image, and the of the FDR schemes performance is significantly influenced, revealing that the accuracy of scalable faces is preserved for features extracted using the DCNN.
In this paper, the purpose of FDR and the distributed environment approach is to improve the processing time to recognize end-user access, which is evaluated in Table 3. The recognition accuracy is preserved for the features extracted using the DCNN by up to 50% of FDR compared to other feature descriptors. The processing time reduces sharply with the preserved recognition accuracy.
Table 3
Performance results of SFAS for a distributed environment using feature dimension reduction
Feature dimension
reduction (%)
|
Recognition
accuracy (%)
|
Recognition time per user (ms)
|
0
|
98.9
|
378
|
10
|
98.4
|
321
|
20
|
97.5
|
256
|
30
|
96.1
|
182
|
40
|
95.3
|
134
|
50
|
91.6
|
114
|
As describe in Fig. 6, the SFAS framework based on this scalability and distributed environment, consists of feature extraction for user-access faces, facial FDR, and classification for authentication. By comparing the experimental results in Tables 1, 2 and 3 for feature extraction, we adopted a DCNN-based feature extraction approach. The concept behind this adoption is its descriptive resistance to dimensionality reduction using PCA because it helps preserve the classification accuracy using the SVM, with a low computational cost. Thus, the combination of the DCNN, PCA and SVM is connected to the proposed scalability algorithm in a distributed environment.
Table 4
Response of the proposed method (SFAS) compared with other related research on FERET dataset
Research
|
Schemes
|
Accuracy
(%)
|
Processing Time
(ms)
|
Xue Lv et al. 2021 [34]
|
LCNN based on R, C-E, and MFGP modules
|
83.5
|
415
|
S.Sharma et al.2020 [35]
|
PCA + SVM
|
96.4
|
398
|
Sahan. J.M et al. 2021 [36]
|
1D-CNN + LDA
|
89.7
|
276
|
Proposed method
|
DCNN + PCA + SVM
with FDR of 50%
|
91.6
|
114
|
As described in Table 4, the experimental results from other related research demonstrate that the proposed approach using the existing combined FR algorithms can achieve better or comparable recognition performance. Furthermore, the SFAS for a distributed environment using FDR was designed to demonstrate that scalability is useful for reducing the FR operation time and preserving the flexibility of the user-access capacity, while maintaining competitive FR performance compared to other methods. Our findings reveal that the Deep Convolutional Neural Network–extracted feature is a stronger illustration of scalability for FDR by using half of the processing time when compared to the facial feature extracted by classical methods.