Thermal Imaging Camera Non-Linear Pixel Signal Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermal imaging cameras face challenges in achieving optimal signal resolution at low object temperatures without signal overload at high temperatures, particularly due to limitations in existing non-linear signal display methods which require compromises between resolution and dynamics.
Innovation Solution
Implementing a method that uses individually tuned, non-linear characteristic curves for each pixel, which can be monotonically increasing or decreasing, with a constant compression parameter up to a threshold and switchable slope options above the threshold, allowing for color representation using a specific color table that assigns gray values, yellow, orange, and red to different temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear signal display with steep characteristic curve is used, then cold objects can be thermally resolved well, but high object temperatures quickly lead to overmodulation
Solution Approach 1:
The patent implements a dynamic, non-linear transfer characteristic that adapts the signal compression based on the input signal strength. The transfer function changes its behavior depending on the temperature range: steeper for cold objects to enhance resolution, and flatter for hot objects to prevent overmodulation. This dynamic adaptation resolves the contradiction by making the system's response characteristic variable rather than fixed.
Solution Approach 2:
The patent modifies the transfer characteristic parameters (slope, curvature) based on the input signal level. By changing the parameters of the transfer function dynamically according to the object temperature, the system achieves optimal resolution for cold objects while preventing signal overload for hot objects. This parameter adaptation directly addresses the technical contradiction.
2Object-affected harmful factors
If a flat characteristic curve optimized for high temperatures is used, then signal overload is prevented, but details of cold objects cannot be seen
Solution Approach 1:
The system dynamically adjusts the transfer characteristic based on the detected temperature range. When cold objects are present, the transfer function adopts a steeper slope to enhance detail visibility. When hot objects dominate, it flattens to prevent overmodulation. This dynamic behavior resolves the contradiction by making the characteristic curve adaptive rather than static.
Solution Approach 2:
The patent employs parameter changes in the transfer function to balance between preventing signal overload and maintaining detail resolution. By varying the slope and curvature parameters according to the scene's temperature distribution, the system optimizes performance for both cold and hot objects, resolving the inherent trade-off.
3Device complexity
If a single linear transfer characteristic is used for all pixels, then device complexity is reduced, but optimal signal resolution cannot be achieved across varying temperature ranges
Solution Approach 1:
The patent applies different transfer characteristics to different pixels based on their local temperature requirements. Each pixel or region can have a customized transfer function optimized for its specific temperature range. This local customization achieves optimal resolution across varying temperatures while the implementation uses efficient algorithms to manage the complexity.
Solution Approach 2:
The patent segments the temperature range and applies different transfer characteristic parameters to different segments. By dividing the temperature spectrum into regions and optimizing the transfer function for each segment, the system achieves high resolution across the full range while managing complexity through structured segmentation rather than completely independent processing for each pixel.
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 optimal signal resolution at low temperatures without signal overload at high temperatures, providing improved image detail and interpretability across varying temperature ranges.
Implementation Method 1
Uncooled thermal imaging cameras use detectors that operate at ambient temperature. All modern uncooled systems work on the principle of changing resistance, voltage or current when the detector is heated by infrared radiation.
Implementation Method 2
The detector cell of a microbolometer array consists of a so-called microbridge structure, which is insulated from the substrate and is connected to the support structure by two conduction paths. The detector element has a higher resistance than the conduction paths, so that the detector element can be measured with a bridge circuit.
Implementation Method 3
Uncooled infrared sensors are kept at a constant temperature by thermoelectric Peltier coolers (TEC) to reduce signal drift of the receiving elements.
Implementation Method 4
A pixel-based non-linear transformation of the input signal intensities into output signal intensities is carried out with the help of a non-linear characteristic. This makes it possible to achieve an optimal signal resolution with minimal effort at low object temperatures, without signal overload occurring at high temperatures.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present invention relates to a thermal imaging camera and a method for producing thermal images with this thermal imaging camera, as described in the generic form of DE 698 30 731 T2. It describes a way to achieve optimal signal resolution at low object temperatures with minimal effort, without signal overload occurring at high temperatures.The task is solved by a method for capturing and reproducing thermal images of a scene and/or object, comprising the following steps: - Creation of a pixel-based thermal image frame using an IR optic and a pixel-based detector unit, - Creation of a dark frame to perform non-uniformity correction (NUC) to eliminate inhomogeneities originating from the detector and/or sources of interference in the optical beam path, - Correction of the resulting pixel-based thermal image frame by weighting the individual pixel signals with a previously generated and stored non-linear characteristic curve to generate a corrected output thermal image, and - final provision of the corrected output thermal image to a display unit or to an interface for external devices.