$\overline{\epsilon }$	Mean relative error
${\epsilon }_{90}$	90th percentile of the relative errors
CCD	Couple-Charged Device
CMOS	Complementary Metal-Oxide Semiconductor
ECG	Electrocardiography
FFT	Fast Fourier transform
FIR	Finite impulse response
GS	Gold standard
HR	Heart rate
IRT	Infrared thermography
OFT	Open Field test
PC	Principal component
PCA	Principal component analysis
PPG	Photoplethysmography
RMSE	Root-mean-square error
ROI	Region of interest
RR	Respiratory rate
SSE	Sum of the squared errors
TI	Thermal image