Standard instrumentation for the assessment of respiration rate is large and based on invasive method, and not suitable
for daily inspection. An optical, simple and non-contact measurement method to detect human respiration rate using lowend
imaging equipment is discussed. This technology is based on the visible light absorption of blood, which contains
many important physiological information of the cardiovascular system. The light absorption of facial area can be
indirectly reflected to gray value of the corresponding area image. In this paper, we acquire the respiration rate through
the video signal captured by low-end imaging equipment. Firstly, the color CCD captures the facial area below the eyes
and every frame of the video can be separated into three RGB channels. The blue channel is extracted as the research
object. Then, we calculate the mean gray value for each image and draw the mean gray curve along the time. Fourier
transform can get the frequency spectrogram of the graph, which is filtered through the Fourier filter. The extreme point
is the value of the respiratory rate. Finally, an available interface program is designed and we have some volunteers
tested. The correlation coefficient between the experimental data and the data provided by a reference instrument is 0.98.
The consistency of the experimental results is very well. This technology costs so low that it will be widely used in
medical and daily respiration rate measurement.
A new cardiac rate measurement method is proposed. Through the beam splitter prism, the common-path optical system
of transmitting and receiving signals is achieved. By the focusing effect of the lens, the small amplitude motion artifact is
inhibited and the signal-to-noise is improved. The cardiac rate is obtained based on the PhotoPlethysmoGraphy (PPG).
We use LED as the light source and use photoelectric diode as the receiving tube. The LED and the photoelectric diode
are on the different sides of the beam splitter prism and they form the optical system. The signal processing and display
unit is composed by the signal processing circuit, data acquisition device and computer. The light emitted by the
modulated LED is collimated by the lens and irradiates the measurement target through the beam splitter prism. The light
reflected by the target is focused on the receiving tube through the beam splitter prism and another lens. The signal
received by the photoelectric diode is processed by the analog circuit and obtained by the data acquisition device.
Through the filtering and Fast Fourier Transform, the cardiac rate is achieved. We get the real time cardiac rate by the
moving average method. We experiment with 30 volunteers, containing different genders and different ages. We compare
the signals captured by this method to a conventional PPG signal captured concurrently from a finger. The results of the
experiments are all relatively agreeable and the biggest deviation value is about 2bmp.