Rearview Mirror Imager Correction for Radial Color Distortion
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Solution Overview
Problem
Transflective coatings in image sensors for vehicle interiors introduce radial color distortion, causing issues such as a green tone in the middle of the image with a pink ring around it and whiter outer parts, due to differential attenuation on individual color channels.
Innovation Solution
A processor determines correction data for each pixel based on its location within the array, applying white-balance operations to correct for radial color distortion using either a look-up table derived from calibration or characterized transmission profiles, accounting for spatial dependencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transflective coating is used in the image sensor to enable simultaneous IR and visible light processing, then the functionality and versatility of the system is improved, but radial color distortion occurs causing green tone in the middle with pink ring and whiter outer parts
Solution Approach 1:
The patent applies different correction values to different regions of the image sensor array. Each pixel or group of pixels has its own correction factors stored in lookup tables, allowing the system to compensate for the spatially varying color distortion caused by the transflective coating. This localised correction approach maintains the coating's optical functionality while restoring color accuracy across different image regions.
Solution Approach 2:
The patent changes the parameters (correction factors) based on the spatial location of pixels within the array. By storing and applying location-dependent correction values in lookup tables, the system dynamically adjusts color values for each pixel based on its position, thereby compensating for the radial color distortion introduced by the transflective coating.
2Device complexity
If the image sensor is positioned behind the electro-optic element to capture images through the transflective coating, then the integration and compactness of the system is improved, but color distortion is introduced requiring complex correction operations
Solution Approach 1:
The patent performs preliminary correction by pre-calculating and storing correction factors in lookup tables before actual image processing. The correction data is prepared in advance based on the known characteristics of the transflective coating and sensor geometry, allowing rapid application during image capture without adding real-time processing complexity.
Solution Approach 2:
The patent introduces lookup tables as an intermediary between the distorted image data and the final corrected output. These tables serve as a mediation layer that maps the spatially varying distortion patterns to appropriate correction factors, simplifying the overall correction process while maintaining 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
Effectively corrects radial color distortion in images captured through transflective coatings, enabling better performance in applications requiring simultaneous IR and visible light processing, such as in-cabin vehicle monitoring.
Implementation Method 1
radial color distortion caused by the transflective coating... due to differential attenuation on individual color channels
Data Source
AI summary
A rearview mirror assembly for a vehicle is provided, including: an electro-optic element having at least one transflective coating; at least one imager comprising an array of pixels and positioned behind the electro-optic element to capture an image through the transflective coating; a processor capable of determining correction data for each pixel as a function of a location of the pixel within the array of pixels; and correcting color values for each pixel of the image captured based on the correction data for that pixel to correct for radial color distortion caused by the transflective coating.