Apparatus and method for determining oxygen saturation with skin tone correction

A method comprising:

• emitting and detecting, by way of first and second probes disposed on a body portion having first through third absorbers, a set of light signals corresponding to a set of wavelengths, wherein the first absorber, the second absorber, and the third absorber is oxyhaemoglobins, deoxyhaemoglobins, and skin/tissues, respectively;
• determining, by way of processing circuitry coupled to the first and second probes, a set of reflectance values and a set of transmittance values based on the set of light signals detected by one of, the first probe, the second probe, or a combination thereof;
• determining and rescaling, by way of the processing circuitry, first and second set of absorbance values corresponding to the set of reflectance values and the set of transmittance values, respectively, wherein each absorbance value of the first and second set of absorbance values are rescaled with respect to predefined absorbance values of the first and second absorbers;
• determining, by way of the processing circuitry, first through third coefficients of the first through third absorbers, respectively, based on the rescaled first and second set of absorbance values;
• and
• determining, by way of the processing circuitry, an oxygen saturation value based on the first and second coefficients such that the oxygen saturation value is corrected for skin and tissue absorption.