Electronic Porthole Correction for Electro-Optical Imagers
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Solution Overview
Problem
Imagers suffer from significant signal rolloff towards the edges due to responsivity distortion, known as the 'porthole' effect, which degrades image presentation and performance, and existing optical correction methods are costly and not suitable for retrofitting existing systems.
Innovation Solution
An electronic system that senses optical system performance, generates spatial correction coefficients to correct nonuniformity, and applies these coefficients to current data to provide inverse distortion, effectively addressing the porthole effect without requiring additional optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If optical approaches are used to correct distortion, then image quality is improved, but cost increases and retrofitting becomes difficult
Solution Approach 1:
The patent replaces optical correction mechanisms with an electronic/digital correction system. Instead of using additional optical components or mechanical adjustments to correct the porthole effect, the invention uses software-based processing of sensor data to generate correction coefficients and apply them to the image signal, thereby eliminating the need for complex optical correction hardware.
Solution Approach 2:
The patent changes the parameters of the imaging system by introducing digitally generated correction coefficients that modify the signal output. These coefficients adjust the gain and offset parameters of the sensor response across different spatial locations, effectively compensating for the nonuniformity without altering the physical optical parameters of the system.
2Reliability
If additional optics are added to correct distortion, then performance is improved, but ease of manufacture and installation deteriorates
Solution Approach 1:
The patent substitutes mechanical/optical correction components with a digital signal processing approach. The correction is achieved through computational algorithms that process the sensor output, eliminating the need to physically modify the optical train or add optical elements, thus enabling easy retrofitting of existing systems.
Solution Approach 2:
The patent creates a universal correction solution that can be applied to various imaging systems through software. The correction coefficients and processing algorithms can be implemented across different sensor types and configurations without requiring system-specific hardware modifications, providing broad applicability and ease of deployment.
3Manufacturing precision
If sensor signal processing compensates for rolled off signal, then image quality is improved, but display dynamic range is wasted
Solution Approach 1:
The patent applies parameter changes to the sensor signal by introducing spatially varying gain and offset corrections. These parameter adjustments redistribute the signal values across the dynamic range, mapping the rolled-off edge signals to utilize the full available display dynamic range, thereby eliminating waste while improving overall image quality.
Data Source
AI summary
An imaging system and method with an arrangement for sensing the performance of an optical system and providing data in response thereto and electronically correcting nonuniformity in the performance of the optical system in response thereto. In the illustrative application, the nonuniformity is a porthole effect. In the preferred embodiment, the arrangement for correcting includes an arrangement for providing an inverse distortion to an output of the system electronically. The inverse distortion is applied by generating a plurality of spatial correction coefficients from the performance data, storing the coefficients and applying the coefficients to current data from the optical system. The spatial correction coefficients are statistically generated gain and level correction defect maps. The present teachings should enable a correction of optical distortion in nonideal electro-optical systems without requiring additional optics.