Spatial-Temporal Image Filter for Thermal Camera Dynamic Error Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Uncooled microbolometer arrays in thermal imaging cameras have long response times, leading to dynamic measurement errors and motion blur when capturing rapidly changing scenes, with no effective solutions for dynamic compensation in the literature, limiting their use in time-critical applications.
Innovation Solution
A method involving a spatial-temporal image filter with adjustable parameters to compensate for the thermal time constant of the sensor elements, reducing dynamic measurement errors and motion blur by reading out the sensor array at a frame rate higher than the characteristic frequency associated with the thermal time constant and applying a matrix-valued transfer function in the image filter to influence the eigenvalues of the convolution matrix.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uncooled microbolometer arrays are used for thermal imaging, then cost is reduced and device complexity is lowered, but response time increases leading to dynamic measurement errors and motion blur
Solution Approach 1:
The patent changes the temporal sampling parameter by reading out the sensor array at a frame rate at least twice the characteristic frequency associated with the thermal time constant. This higher sampling rate captures more data points during the sensor's thermal response, enabling accurate dynamic measurements despite the inherent thermal inertia of uncooled microbolometer arrays.
Solution Approach 2:
The patent applies preliminary digital signal processing in the form of a spatial-temporal image filter that compensates for the thermal time constant effects before final image generation. By pre-processing the raw sensor data with appropriate filtering algorithms, the system removes dynamic measurement errors and motion blur artifacts, restoring measurement accuracy.
2Device complexity
If uncooled microbolometer arrays are used, then device complexity is reduced, but response speed decreases due to thermal inertia
Solution Approach 1:
The patent replaces physical hardware modifications with digital signal processing methods. Instead of modifying the thermal properties of the microbolometer array or using mechanical cooling systems, the invention uses computational algorithms to compensate for thermal inertia effects, achieving fast response performance through software rather than hardware changes.
Solution Approach 2:
The patent introduces a temporal dimension to the image processing by applying spatial-temporal filtering. By considering not just spatial relationships between pixels but also temporal relationships across multiple frames, the system compensates for the slow thermal response, effectively adding time as a dimension for error correction.
3Ease of manufacture
If thermal IR image sensors with thermal inertia are used, then manufacturing cost is reduced, but measurement precision for rapidly moving scenes deteriorates
Solution Approach 1:
The patent implements feedback through iterative optimization of the spatial-temporal image filter. The filter parameters are adjusted based on the observed thermal response characteristics, and the filtering process continuously refines the temperature measurements by comparing expected versus actual sensor responses, thereby compensating for thermal inertia effects and improving radiometric 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
This approach significantly reduces dynamic measurement errors and motion blur, enabling faster and more accurate thermal imaging by compensating for the thermal inertia of the sensor pixels through digital image processing, allowing for precise measurements and improved image quality in time-critical tasks.
Implementation Method 1
Recording an IR scene using a thermal IR image sensor (1)
Implementation Method 2
The parameters of the image filter for influencing the eigenvalues of the at least one convolution matrix are expediently adapted by numerically solving the system of linear equations
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a method and a thermal imaging camera for non-contact temperature measurement or for observing rapidly moving IR scenes with a thermal IR image sensor. The object of the invention, to find a new way to correct the dynamic inertia of thermal IR sensor arrays, thereby reducing the dynamic measurement errors of a thermal imaging camera, is achieved according to the invention by placing a spatial-temporal image filter downstream of the output of the IR image sensor. This filter is configured to implement a matrix-valued transfer function, wherein the calculations for each result pixel value take into account the current sensor pixel value, a number of earlier sensor pixel values, a number of adjacent sensor pixel values, and a number of earlier adjacent sensor pixel values. Furthermore, the matrix-valued transfer function includes adjustable parameters.which characterizes the response behavior of each individual corrected result pixel value, wherein the adaptation of the filter characteristic to a specific measurement task is achieved by influencing the position of eigenvalues of at least one convolution matrix in order to adapt at least zeros or poles in the transfer function of the image filter configuration.