## 5 Discussion  
This study improved many methods of the algorithm flow, as shown in the comparison table of performance algorithm flow, which compared the algorithm flow for the extracted physiological signal of this study with that of [PERSON] et al. [5] and [PERSON] et al. [7]. This paper adjusted the wavefront levels through a detrended fluctuation analysis, which could improve the accuracy of the heart rate and HRV. Additionally, the proposed PSO-ICA could substantially reduce the computing time of the system and improve the problem of ICA iterating locally optimal solutions in the case of poor initial values. In the meantime, expanding the ROI from capturing the forehead to the forehead plus cheeks confirmed that the measurement accuracy could be improved by capturing the forehead plus cheeks. The  
Figure 12: Histogram of FastICA and PSO-ICA time statistics. results showed a heart rate error of 2%, indicating a decline of 4.038% from the error of the previous forehead measurement. Nowadays, physiological parameters are mainly measured with contact light volume descriptors using electrocardiograms, ultrasonic sensors, or piezoelectric sensors. In recent years, the research literature has explored the performance and error of non-contact measurements and the comparison with the above techniques. As shown in Table 4, compared with the study results of other scholars, the mean absolute percentage error of the heart rate measurements proposed in this study was validated by a medical device licensed by the Ministry of Health and Welfare in Taiwan at 2%, less than the error values of the methods proposed by other scholars. In addition, the time required for taking a measurement using the method put forward by this study was shorter than those proposed by other scholars. * This paper only takes the staff and students of a university in the south as the experimental data objects. * The experimental distance in this paper is 50 cm\(\sim\)100 cm, if it exceeds the range, it will affect the experimental value. * Since the light in this research will affect the experimental results, the research is only carried out in a bright place under the illumination of 350-550 lux. * During the measurement process of this paper, try to keep still and breathe spontaneously, and do not shake excessively, turn the face or shift the detection angle, which will cause misjudgment. Currently on the market, the signal of the contact optical volumetric descriptor is combined with the electrocardiogram, ultrasonic sensor, or piezoelectric sensor to measure physiological parameters. In recent years, research literature discusses non-contact measurement. The measurement performance and error, as well as the comparison with the above-mentioned related technologies, as shown in Table 5. The research results of this paper are compared with that of other scholars. The heart rate measurement proposed in this paper is verified by the medically licensed instrument of the Taiwan Department of Health. The MAPE is 2.2%. The error value of the method proposed by other scholars is smaller, and the time required for its measurement is shorter than the method proposed by other scholars. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Function** & **Present Study** & **[PERSON]. [5]** & **[PERSON]. [7]** \\ \hline Take out the face part & Partial & full face & full face \\  & & (Without facial features) & (Without facial features) \\ \hline Signal Adjustment Level & YES & NO & NO \\ \hline ICA & PSO-ICA & JBSS-ICA & JADE-ICA \\ \hline Bandpass filter & 0.4–10 Hz & NO & 0.7–4 Hz \\ \hline HRV Formula & YES & NO & NO \\ \hline Continuous measurement of & YES & NO & NO \\ physiological parameters & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Algorithm process comparison table.