Shutterless IR Camera Calibration via Visible Light Feature Detection
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Solution Overview
Problem
Shutterless thermography arrangements face challenges in maintaining accurate calibration due to temperature drifts and non-uniformities in infrared radiation detection, as they lack a mechanical shutter for reference calibration.
Innovation Solution
The method involves capturing both infrared (IR) and visible light (VL) images of a scene, using a processor to determine predefined features in both images, performing a VL-to-IR image coordinate transform, and calibrating the IR imaging system based on the captured IR data values and a predetermined temperature value associated with the feature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a mechanical shutter is removed to reduce moving parts, system weight and power consumption, then device complexity and power consumption are reduced, but calibration accuracy deteriorates due to inability to obtain reference measurements
Solution Approach 1:
The patent introduces a visible light (VL) imaging system as an intermediary to detect predefined features (such as human faces) that serve as calibration references. The VL system acts as a mediator to identify features with known temperature characteristics, enabling the IR system to obtain reference measurements without a mechanical shutter. This resolves the contradiction by providing calibration capability through a different imaging modality rather than mechanical means.
Solution Approach 2:
The patent replaces the mechanical shutter system with a computational approach using VL and IR image processing. Instead of using mechanical components to block and reference calibration, the system uses algorithmic feature detection, coordinate transformation, and pixel value comparison to achieve calibration. This substitution eliminates moving parts while maintaining calibration functionality through software-based reference identification.
2Ease of manufacture
If conventional calibration methods using controlled environment data are used, then initial calibration can be performed, but calibration accuracy deteriorates in varying real-world environments due to temperature drifts and non-uniformities
Solution Approach 1:
The patent enables the IR imaging system to perform self-calibration in real-world environments by detecting features with known temperature characteristics through the VL system. Instead of relying on pre-determined calibration curves from controlled environments, the system automatically identifies reference features (such as human faces with known temperature ranges) and uses them to adjust calibration parameters on-the-fly. This self-service capability maintains reliability across varying environments without requiring periodic re-calibration in controlled settings.
Solution Approach 2:
The patent implements a feedback mechanism where the system continuously monitors IR pixel values of detected features, compares them against expected temperature values, and adjusts calibration parameters accordingly. The VL system provides feedback on feature detection and positioning, while the IR system provides feedback on temperature measurements. This closed-loop feedback enables dynamic calibration adjustment to compensate for temperature drifts and environmental variations, maintaining calibration stability without mechanical shutters or controlled environment re-calibration.
3Measurement precision
If calibration is performed frequently to maintain accuracy, then measurement precision is maintained, but productivity decreases due to time loss from repeated calibration procedures
Solution Approach 1:
The patent enables continuous calibration by detecting features in each captured image frame and updating calibration parameters in real-time. Instead of performing discrete calibration procedures at intervals, the system continuously monitors for features with known temperature characteristics and adjusts calibration parameters ongoingly. This continuous useful action maintains measurement precision without periodic interruptions, as the calibration process becomes an ongoing background operation rather than a repeated procedural step.
Solution Approach 2:
The patent performs preliminary detection of features with known temperature characteristics through the VL system before IR temperature measurement is required. By pre-identifying calibration reference features and their expected temperature values, the system prepares calibration data in advance, enabling rapid calibration adjustment when needed. This preliminary action reduces the time required for calibration procedures, as the reference feature identification and coordinate transformation are already completed before temperature measurement and calibration application.
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
This approach enables improved calibration of IR imaging systems in shutterless thermography arrangements by minimizing differences in captured infrared data values, thereby correcting for temperature drifts and non-uniformities, ensuring accurate radiometric measurements across varying environments.
Implementation Method 1
capturing an infrared (IR) image depicting an observed real world scene using an infrared (IR) imaging system, wherein the captured IR image comprises captured infrared data values of infrared (IR) radiation emitted from the observed real world scene
Data Source
AI summary
A method for improved calibration of captured infrared data values by an IR imaging system in a thermography arrangement dependent on an infrared (IR) image depicting an observed real world scene. The IR image may be captured by a thermography arrangement including the IR imaging system, wherein infrared (IR) image is related to temperature dependent on IR calibration parameters. A predefined feature may be detected from the IR image, and the IR imaging system may be calibrated based on the predefined feature.