Radiometric Camera Self-Calibration via Gamma Drift Estimation
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Solution Overview
Problem
Existing infrared camera systems for detecting infectious diseases face challenges in achieving accurate temperature measurements in high-traffic areas due to the need for external calibration using multiple blackbodies, which complicates operation and increases costs.
Innovation Solution
A radiometric camera system that estimates a gamma drift coefficient from thermal images, performs sensor temperature stabilization, and conducts ambient calibration to measure object temperatures independently of the camera's ambient temperature, eliminating the need for external calibration sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external calibration components (blackbodies) are used to achieve accurate temperature measurements, then measurement precision is improved, but device complexity and operational complexity increase
Solution Approach 1:
The patent extracts the calibration function from external blackbody components and relocates it to internal elements within the camera system. The shutter and specific pixels are utilized as internal calibration references, eliminating the need for separate external calibration devices and simplifying the overall system architecture while maintaining measurement accuracy.
Solution Approach 2:
The shutter mechanism serves dual purposes: it acts as both an operational component for capturing thermal images and as a calibration reference element. By making the shutter multi-functional, the system reduces the total number of components needed and simplifies the calibration process without compromising temperature measurement precision.
2Measurement precision
If multiple blackbodies are used for calibration, then measurement precision is improved, but ease of operation deteriorates due to adjustment and stabilization requirements
Solution Approach 1:
The system performs calibration automatically using its own internal resources (shutter and pixels) without requiring external calibration equipment or manual adjustment procedures. The camera self-calibrates by utilizing the known thermal characteristics of its shutter and specific pixels, eliminating the need for operators to manually position and stabilize external blackbodies.
Solution Approach 2:
The calibration data is captured and stored in advance during manufacturing or initial setup, allowing the system to perform rapid automated calibration during operation. This preliminary preparation eliminates the need for time-consuming manual calibration procedures and stabilisation waiting periods during actual use.
3Measurement precision
If external calibration sources are required, then measurement precision is improved, but cost increases
Solution Approach 1:
The shutter and pixels serve multiple functions including both operational imaging and calibration reference, eliminating the need for separate expensive external calibration equipment. This multi-functionality reduces the overall system cost while maintaining the precision benefits of calibration.
Solution Approach 2:
The patent utilizes inexpensive internal components (shutter, pixels) that are already part of the camera system for calibration purposes, replacing the need for expensive external blackbody calibration sources. This approach significantly reduces the overall system cost while maintaining calibration accuracy.
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
Enables accurate and efficient simultaneous temperature measurements of multiple objects, improving detection accuracy and reducing operational complexity and costs by eliminating the requirement for external calibration sources.
Implementation Method 1
A typical IR camera uses an infrared sensor to detect infrared energy that is guided to the sensor through the camera's lens
Implementation Method 2
A blackbody at thermal equilibrium (a constant temperature) emits electromagnetic radiation called black-body radiation. The radiation has a spectrum that is determined by the temperature alone
Data Source
AI summary
A radiometric camera and method for obtaining accurate radiometric readings of objects in a scene captured by a radiometric camera. The method comprises estimating a gamma drift coefficient based on an input thermal image, wherein the thermal image is captured by an infrared sensor; performing, based on the gamma drift coefficient and the input thermal image, a sensor temperature stabilization to provide an ambient-stabilized thermal image, wherein the ambient-stabilized thermal image is invariant to temperature changes of the infrared sensor; performing ambient calibration to estimate a scene temperature based on the ambient-stabilized thermal image; and measuring, based on the estimated scene temperature and a calibrated attenuation factor, a temperature of each of at least one object shown in the input thermal image, where the temperature of each of the at least one object is measured independently of the ambient temperature of the radiometric camera.