Forehead Temperature Calibration Using Visual-Thermal Mapping
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Solution Overview
Problem
Auto forehead temperature measuring systems suffer from inaccurate temperature measurements due to fixed, and fluctuating environmental temperature fluctuations, resulting in false alarms and degraded measurement accuracy.
Innovation Solution
A temperature measurement system that compensates or calibrates temperature deviations caused by distance and environmental temperature fluctuations using an image sensor and a thermal sensor, which includes a substrate, a thermal sensor and an image sensor, and a processor, which recognizes a forehead region in an image frame, maps a pixel range of the forehead region in the thermal image to determine a mapped region as a determined temperature measuring range of the thermal sensor, and calibrates the measured forehead temperature according to a predetermined calibration temperature obtained using a predetermined heated region, configured to be captured by the image sensor and the thermal sensor in a setting stage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a thermal sensor is used to measure forehead temperature from a distance, then non-contact measurement is achieved, but measurement accuracy deteriorates due to environmental temperature fluctuations and distance variations
Solution Approach 1:
An image sensor is introduced as an intermediary to capture visual information of the forehead region. The processor uses this visual information to identify the forehead area in the thermal image, enabling accurate temperature measurement without direct contact. This mediator helps distinguish the target measurement area from environmental interference.
Solution Approach 2:
The system performs preliminary identification of the forehead region using image sensor data before measuring temperature. By pre-locating the forehead area through visual recognition, the system ensures that the subsequent thermal measurement is focused on the correct region, improving accuracy despite distance and environmental variations.
2Adaptability or versatility
If the field of view covers environmental objects, then auto measurement is enabled, but measurement accuracy deteriorates due to interference from non-forehead objects
Solution Approach 1:
The thermal image is segmented into different regions based on visual information from the image sensor. The processor identifies which portion of the thermal image corresponds to the forehead by matching it with the visual forehead region, separating the target measurement area from environmental objects in the field of view.
Solution Approach 2:
Different regions of the thermal image are treated differently based on their identification. The forehead region is selected for temperature measurement while other regions (environmental objects) are excluded. This local differentiation ensures accurate measurement despite a broad field of view.
3Adaptability or versatility
If distance between measured person and system varies, then flexible measurement is achieved, but measurement accuracy deteriorates due to position offset between sensors
Solution Approach 1:
The system dynamically adjusts the mapping between image sensor pixels and thermal sensor pixels based on the detected distance. When distance varies, the processor recalculates the correspondence relationship, ensuring that the forehead region in the thermal image accurately matches the visual forehead region regardless of distance changes.
Solution Approach 2:
The system changes the mapping parameters (pixel correspondence) based on distance variations. By adjusting these parameters dynamically, the system maintains accurate alignment between visual and thermal images even when the distance between the measured person and the system changes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The technical solution effectively compensates or calibrates the measured temperature deviations caused by the distance from a measured person and by the environmental temperature fluctuations by using an image sensor, which compensates or calibrates the temperature deviation caused by the distance and by the environmental temperature fluctuation, thereby improving the measurement accuracy of the auto forehead temperature measuring system.
Implementation Method 1
The thermal sensor is configured to receive optical energy via the lens to output thermal images
Implementation Method 2
The image sensor is configured to receive optical energy via the lens to output image frames
Data Source
AI summary
There is provided a temperature measurement system including an image sensor, a thermal sensor and a processor. The image sensor captures an image frame. The thermal sensor captures a thermal image. The processor calibrates measured temperatures of the thermal sensor and calibrates offset pixels between the image frame and the thermal image corresponding to different operating distances.