Distance compensation for thermal imaging temperature measurement of inner canthus systems and methods
Various techniques are disclosed to provide for improved human body temperature detection using thermal images of an inner canthus. In one example, a method includes capturing a thermal image of a human being using a thermal imager. The method also includes determining an uncompensated temperature measurement associated with an inner canthus of a face of the human being using corresponding pixels of the thermal image. The method also includes determining a correction term as a function of a distance between the thermal imager and the human being. The method also includes applying the correction term to the uncompensated temperature measurement to provide a corrected temperature measurement associated with the inner canthus to compensate for attenuation associated with the distance. Additional methods and systems are also provided.
1 . A method comprising:
capturing a thermal image of a human being using a thermal imager;
determining an uncompensated temperature measurement associated with an inner canthus of a face of the human being using corresponding pixels of the thermal image;
preprocessing a plurality of initial thermal images of a plurality of subjects to determine one or more fitting constants based on a correlation between a distance and a face width of each of the plurality of subjects;
determining a correction term as a function of the one or more fitting constants and the distance between the thermal imager and the human being, wherein determining the correction term includes determining a number of pixels of the thermal image associated with a width of the face; and
applying the correction term to the uncompensated temperature measurement to provide a corrected temperature measurement associated with the inner canthus to compensate for attenuation associated with the distance.
2 . The method of claim 1 , further comprising:
determining the distance using a predetermined association between the number of pixels and the distance.
3 . The method of claim 1 , wherein the width of the face comprises an ear-to-ear width.
4 . The method of claim 1 , further comprising detecting the face of the human being and the inner canthus in the thermal image.
5 . The method of claim 4 , wherein the detecting comprises processing the thermal image by an artificial neural network.
6 . The method of claim 1 , further comprising:
determining, using a statistical model, a threshold based on a running average of a determined body temperature; and
determining an elevated body temperature of the human being using the corrected temperature measurement by determining if the corrected temperature measurement exceeds the threshold.
7 . The method of claim 6 , further comprising generating a notification to inform a user of the thermal imager of the elevated body temperature.
8 . The method of claim 1 , further comprising repeating the method for a plurality of human beings at a plurality of distances from the thermal imager.
9 . The method of claim 1 , wherein the method is performed by a portable thermal camera comprising the thermal imager.
10 . The method of claim 1 , further comprising:
detecting a face covering worn by the human being;
determining one or more properties of the face covering, wherein the one or more properties comprise type, color, material, and/or position of the face covering relative to the inner canthus; and
determining the correction term as a function of the one or more properties of the face covering.
11 . A system comprising:
a thermal imager; and
a logic device configured to:
operate the thermal imager to capture a thermal image of a human being,
determine an uncompensated temperature measurement associated with an inner canthus of a face of the human being using corresponding pixels of the thermal image,
preprocess a plurality of initial thermal images of a plurality of subjects to determine one or more fitting constants based on a correlation between a distance and a face width of each of the plurality of subjects;
determine a correction term as a function of the one or more fitting constants and the distance between the thermal imager and the human being, wherein determining the correction term includes determining a number of pixels of the thermal image associated with a width of the face, and
apply the correction term to the uncompensated temperature measurement to provide a corrected temperature measurement associated with the inner canthus to compensate for attenuation associated with the distance.
12 . The system of claim 11 , wherein the logic device is configured to:
determine the distance using a predetermined association between the number of pixels and the distance.
13 . The system of claim 11 , wherein the width of the face comprises an ear-to-ear width.
14 . The system of claim 11 , wherein the logic device is configured to detect the face of the human being and the inner canthus in the thermal image.
15 . The system of claim 14 , wherein the logic device is configured to process the thermal image by an artificial neural network to detect the face and the inner canthus.
16 . The system of claim 11 , wherein the logic device is configured to:
determine, using a statistical model, a threshold based on a running average of a determined body temperature; and
determine an elevated body temperature of the human being using the corrected temperature measurement by determining if the corrected temperature measurement exceeds the threshold.
17 . The system of claim 16 , wherein the logic device is configured to generate a notification to inform a user of the thermal imager of the elevated body temperature.
18 . The system of claim 11 , wherein the logic device is configured to determine corrected temperature measurements for a plurality of human beings at a plurality of distances from the thermal imager.
19 . The system of claim 11 , wherein the system is a portable thermal camera.
20 . The system of claim 11 , wherein the logic device is configured to:
detect a face covering worn by the human being;
determine one or more properties of the face covering, wherein the one or more properties comprise type, color, material, and/or position of the face covering relative to the inner canthus; and
determine the correction term as a function of the one or more properties of the face covering.