Camera based photoplethysmogram estimation
First Claim
Patent Images
1. A method of estimating a photoplethysmogram (PPG) waveform of a target, comprising:
- obtaining a plurality of images, wherein an image of the plurality of images comprises the target;
subdividing the target into a plurality of portions;
determining, based on the plurality of images, a time variation of a light reflectivity of a portion of the plurality of portions;
determining, based on the time variation of the light reflectivity, a weight associated with the portion of the plurality of portions; and
estimating the PPG waveform of the target based on the weight and the image of the plurality of images,wherein estimating the PPG waveform of the target comprises multiplying the weight of the portion of the plurality of portions by the light reflectivity of the portion of the plurality of portions to form a weighted light reflectivity of the portion.
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Abstract
A system for estimating a photoplethysmogram waveform of a target includes an image processor configured to obtain images of the target and a waveform analyzer. The waveform analyzer is configured to determine a weight of a portion of the target. The weight is based on a time variation of a light reflectivity of the portion of the target. The time variation of the light reflectivity of the target is based on the images. The waveform analyzer is further configured to estimate a PPG waveform of the target based on the weight of the portion and the time variation of the light reflectivity of the portion.
3 Citations
18 Claims
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1. A method of estimating a photoplethysmogram (PPG) waveform of a target, comprising:
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obtaining a plurality of images, wherein an image of the plurality of images comprises the target; subdividing the target into a plurality of portions; determining, based on the plurality of images, a time variation of a light reflectivity of a portion of the plurality of portions; determining, based on the time variation of the light reflectivity, a weight associated with the portion of the plurality of portions; and estimating the PPG waveform of the target based on the weight and the image of the plurality of images, wherein estimating the PPG waveform of the target comprises multiplying the weight of the portion of the plurality of portions by the light reflectivity of the portion of the plurality of portions to form a weighted light reflectivity of the portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A non-transitory computer readable medium (CRM) storing instructions for estimating a photoplethysmogram (PPG) waveform of a target, the instructions comprising functionality for:
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obtaining a plurality of images, wherein an image of the plurality of images comprises the target; subdividing the target into a plurality of portions; determining, based on the plurality of images, a time variation of a light reflectivity of a portion of the plurality of portions; determining, based on the time variation of the light reflectivity, a weight associated with the portion of the plurality of portions; and estimating the PPG waveform of the target based on the weight and the image of the plurality of images, wherein the instructions for determining the time variation of the light reflectivity of the portion of the plurality of portions comprise functionality for; identifying the target in each image of the plurality of images; generating an alignment transformation for each image of the plurality of images based on the location of the target in the image of the plurality of images; applying the alignment transform to each image of the plurality of images to associate at least one pixel of each image of the plurality of images with the target; and determining the time variation of the light reflectivity of the portion of the plurality of portions based on the at least one pixel of each image of the plurality of each image and a capture time of each image of the plurality of images. - View Dependent Claims (10)
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11. A method of estimating a photoplethysmogram (PPG) waveform of a target, comprising:
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obtaining a plurality of images, wherein an image of the plurality of images comprises the target; subdividing the target into a plurality of portions; determining, based on the plurality of images, a time variation of a light reflectivity of a portion of the plurality of portions; determining, based on the time variation of the light reflectivity, a weight associated with the portion of the plurality of portions; estimating the PPG waveform of the target based on the weight and the image of the plurality of images; generating an estimate of a frequency of the PPG waveform based on the filtered light reflectivity of the portion of plurality of portions; applying a bandpass filter to the filtered time variation of the light reflectivity of the portion of the plurality of portions to generate a filtered time variation of the light reflectivity, wherein a passband of the bandpass filter comprises the estimate of the frequency of the PPG waveform; determining a first spectral power of the filtered time variation of the light reflectivity of the portion of the plurality of portions in a spectral region including the estimate of the frequency of the PPG waveform; determining a second spectral power of the filtered time variation of the light reflectivity of the portion of the plurality of portions in a spectral region that does not include the estimate of the frequency of the PPG waveform; and determining the weight based on the first spectral power and the second spectral power. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification