Spatial Filter for Infrared Gas Imaging Contrast
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Solution Overview
Problem
Infrared imaging systems face challenges in distinguishing gas features from other scene content due to high dynamic range and low contrast, as existing processing techniques like histogram equalization and temporal difference processing are either ineffective or computationally demanding.
Innovation Solution
A method involving a spatial filter is applied to infrared images to enhance gas contrast by removing scene features, thereby isolating the gas feature and mapping its pixel values to a larger temperature range, increasing visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If histogram equalization processing is applied to increase gas contrast, then gas visibility is improved, but all spatial frequencies are affected and it becomes computationally demanding when applied locally
Solution Approach 1:
The image processing is divided into two distinct stages: first applying histogram equalization globally to the entire image to enhance overall contrast, then applying a spatial filter locally to specific regions containing gas features. This segmentation allows the computationally intensive histogram equalization to be performed once on the whole image, while subsequent local processing is much less demanding.
Solution Approach 2:
The patent applies different processing characteristics to different regions of the image. The spatial filter is applied locally to regions where gas features are detected, rather than processing the entire image with the same intensive operations. This local quality approach reduces overall computational demand while maintaining gas contrast enhancement where needed.
2Measurement precision
If temporal difference processing is used to remove static content, then static scene features are eliminated, but the processed images change too rapidly and become difficult to understand in context
Solution Approach 1:
The patent employs adaptive processing that adjusts the degree of temporal differencing based on detected gas features. When gas is detected, the system maintains more temporal variation to preserve gas visibility. When no gas is present, it applies stronger temporal filtering to remove static content. This dynamic adjustment maintains both detection accuracy and interpretability across different scenarios.
3Measurement precision
If manual settings of level and span are used to adjust gas contrast, then gas visibility can be improved, but it becomes difficult and time consuming for users to manipulate
Solution Approach 1:
The system automatically performs histogram equalization and spatial filtering operations to enhance gas contrast without requiring manual user adjustment. The algorithm autonomously identifies gas features and applies appropriate processing parameters, eliminating the need for users to manually manipulate level and span settings while still achieving improved gas visibility.
4Loss of information
If the full dynamic range of pixel values is preserved in the image, then all scene features are captured, but the gas feature exhibits low contrast and is not easily distinguishable
Solution Approach 1:
The spatial filter extracts and isolates the gas feature from the full scene by filtering out static non-gas content. This extraction process separates the gas signal from the background, allowing the gas to be visualized with enhanced contrast while the full scene information is preserved in the unprocessed or differently processed display outputs.
Data Source
AI summary
Various techniques are provided for increasing contrast of gas features in a scene. In one example, a method includes receiving a captured infrared image comprising a gas feature and a scene feature. The captured infrared image comprises a first range of pixel values associated with a first temperature range of the gas feature and the scene feature. The method also includes applying a spatial filter to the captured infrared image to provide a spatially filtered infrared image retaining the gas feature and removing the scene feature. The spatially filtered infrared image comprises a second range of pixel values associated with a second temperature range of the gas feature without the additional scene feature to exhibit increased gas contrast over the captured infrared image. Additional methods and systems are also provided.