Infrared Camera Stray Light Compensation via Software Extraction
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Solution Overview
Problem
Infrared (IR) cameras face challenges with stray light compensation, particularly in uncooled cameras where spatial noise and production costs are high due to temperature mismatches between the camera spade and the scene, and existing offset calibration methods introduce new stray light issues when defocusing.
Innovation Solution
A process that measures stray light images at different camera temperatures, filters and matches selections to eliminate deviant forms, and compensates images using a calculated factor, allowing for real-time compensation without a shutter, and can be coordinated with offset calibration or Non-Uniformity Correction (NUC) techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offset calibration is performed using a spade, then calibration accuracy is improved, but spatial noise increases due to temperature mismatch between spade and scene
Solution Approach 1:
The patent extracts and removes the spade component from the calibration system entirely. Instead of using a physical spade insert, the method uses software-based stray light compensation by measuring and subtracting stray light patterns from calibration images, thereby eliminating the source of spatial noise while maintaining calibration accuracy.
Solution Approach 2:
The patent replaces the mechanical spade insertion and physical calibration method with an optical/software-based approach. The system captures images without a spade, processes them computationally to separate and remove stray light effects, and achieves calibration through algorithmic manipulation rather than physical obstruction.
2Object-affected harmful factors
If defocusing is used for offset calibration, then high-frequency noise is removed, but new stray light is introduced from the defocused state
Solution Approach 1:
The patent performs preliminary measurements of stray light patterns under controlled conditions (with and without defocusing) before actual calibration. These pre-measured stray light patterns are stored and then subtracted from calibration images, allowing the system to compensate for stray light effects without needing to physically block them or introduce additional components.
Solution Approach 2:
The patent implements a feedback mechanism where stray light patterns measured during calibration are fed back into the image processing system. The measured stray light patterns are subtracted from subsequent calibration images, continuously correcting for stray light effects and maintaining calibration accuracy while allowing the camera to operate in its normal focused state.
3Ease of manufacture
If a spade is used for calibration, then calibration can be performed, but production cost increases due to transport mechanisms
Solution Approach 1:
The patent removes the spade and its associated transport mechanisms from the system. Calibration is achieved by capturing images of the scene without any physical calibration objects, processing these images computationally to separate signal from stray light, and deriving calibration parameters algorithmically. This eliminates mechanical components and reduces production complexity.
Solution Approach 2:
Instead of using a physical spade, the patent creates a digital representation or model of the calibration process through software algorithms. The system captures the optical response characteristics by processing images computationally, creating a digital calibration model that replaces the need for physical calibration hardware and its associated mechanical transport systems.
Data Source
AI summary
Various techniques are provided for a stray light compensation method for an infrared (IR) camera. For example, a stray light compensation method includes: capturing an IR image of a scene by an IR camera, generating a fixed pattern noise estimate FPNestt0 for time t0 using the captured IR image and a stray light model associated with the IR camera, and performing a fixed pattern noise (FPN) compensation of the captured IR image based on said FPNestt0 to obtain a stray light compensated IR image. The fixed pattern noise estimate may be generated through operations in a frequency domain representation of the captured IR image and the stray light model according to one or more embodiments.