  The near infrared scattering images of human muscle include some information
on bloodstream and hemoglobin concentration according to skin depth and time.
This paper addressed a method of determining oxygen saturation and
photoplethysmogram from the near infrared (NIR) scattering images of muscle.
Depending on the modified Beer-Lambert Law and the diffuse scattering model of
muscular tissue, we determined an extinction coefficient matrix of hemoglobin
from the near infrared scattering images and analyzed distribution of oxygen
saturation of muscle with a depth from the extinction coefficient matrix. And
we determined a dynamic attenuation variation curve with respect to fragmentary
image frames sensitive to bloodstream from scattering image frames of muscle
with time and then obtained the photoplethysmogram and heart rate by Fourier
transformation and inverse transformation. This method based on the NIR
scattering images can be applied in measurement of an average oxygen saturation
and photoplethysmogram even in local region of optically heterogeneous muscle
and skin.
