#$%^&*AU2010219290A120120322.pdf#####ABSTRACT APPARATUS AND METHOD FOR ORTHOGONALIZING SIGNALS DETECTING BLOOD OXYGENATION AND BLOOD VOLUME A filter for detecting changes in skin color is described. The filter (100) includes a filter material (110) capable of filtering a frequency range and configured to orthogonalize an overall red response and an overall blue response in response to a spectral power distribution of a given light condition. The overall red response is based on a first plurality of spectral responses for a first human perceived chromatic channel used primarily for detecting blood oxygenation in a human. The overall blue response is based on a second plurality of spectral responses for a second human perceived chromatic channel used primarily for detecting blood volume.2/13 200 Start Receiving a Light Signal as an Input 210 Filtering a Frequency Range of the Light Signal through a Filter to Generate a Modified Light Signal, Wherein the Filter Orthogonalizes an Overall Red Response Indicating a Change in Blood Oxygenation and an Overall Red Response Indicating a Change in Blood Volume, wherein the Overall Red Response is based on a First Plurality of Spectral Reponses for a First Human Perceived Chromatic Channel 220 Primarily Used for Detecting Blood Oxygenation in a Skin of a Human, and Wherein the Overall Blue Response is based on a Second Plurality of Spectral Responses for a Second Human Perceived Chromatic Channel Used Primarily for Detecting Blood Volume Outputting the Modified Light Signal from the Filter 230 End Fg2 Fig. 2
