Image Sensor Flicker Correction Using Exposure Series Masks
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Solution Overview
Problem
Existing image sensors capture images of pulsed light sources, such as LEDs, incorrectly due to their short exposure times and varying pulse frequencies, leading to flickering light information that causes image errors, particularly in automotive applications, which can compromise safety.
Innovation Solution
A method involving an exposure series with at least one reference image and multiple comparison images of varying exposure times is used to detect and correct flickering light information by determining local deviations and generating an error mask, followed by applying local correction values to the comparison images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the exposure time of the image sensor is extended to capture pulsed light sources, then the light information is captured more reliably, but the image sensor cannot capture other moving objects in the scene and the temporal resolution is reduced
Solution Approach 1:
The patent divides the image capture process into multiple exposure series, each with different exposure times. By segmenting the capture of pulsed light sources into multiple temporal samples, the system achieves both reliable light information capture and maintains temporal resolution through parallel processing of multiple exposure sequences.
Solution Approach 2:
The patent employs periodic sampling of the pulsed light sources by capturing multiple exposure series at different time points. This periodic action allows the system to track the temporal behavior of flickering lights while maintaining the ability to capture other scene dynamics, resolving the contradiction between reliability and temporal resolution.
2Measurement precision
If multiple exposure series with different exposure times are captured, then flickering light information can be detected and corrected, but the data processing complexity and computational load increase
Solution Approach 1:
The patent performs preliminary organization of multiple exposure series into structured data formats before detailed analysis. By pre-processing and arranging the exposure data in an optimized structure, the system reduces the computational complexity of subsequent flicker detection and correction operations, maintaining high measurement precision while managing processing complexity.
Solution Approach 2:
The patent creates simplified representations or models of the exposure series data for analysis purposes. By working with copied or modeled data structures rather than raw multi-exposure data throughout the processing pipeline, the system reduces computational load while preserving the accuracy needed for flicker detection.
3Reliability
If the exposure time is extended to ensure capture of pulsed light sources, then image errors caused by flicker are reduced, but motion blur increases for moving objects
Solution Approach 1:
The patent dynamically adjusts exposure times across multiple exposure series, using short exposure times for capturing moving objects to maintain sharpness, and longer exposure times selectively for pulsed light sources to ensure reliable capture. This dynamic approach resolves the contradiction by allowing different exposure parameters for different capture goals within the same system.
Solution Approach 2:
The patent applies different exposure time settings to different regions or targets within the scene. By optimizing exposure parameters locally for pulsed light sources versus moving objects, the system achieves reliable light capture without compromising overall image sharpness, as each region receives the exposure treatment it specifically requires.
Data Source
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AI summary
A method for detecting and correcting image errors caused by flickering light information (1,2) in images (Si,VSi) generated by an image sensor (10) is described. The procedure comprises the following steps: - Reading in an exposure series that includes at least one reference image (Li) and at least one comparison image (Si,VSi), wherein the images of the exposure series show the same scene (4) and the exposure time of the reference image (Li) is longer than the exposure time of the comparison image (Si,VSi), - Determining spatial deviations of the image data of the comparison image (Si,VSi) from the image data of the reference image (Li) by spatially comparing the image data of the comparison image (Si,VSi) with the image data of the reference image (Li), - Generating an error mask (E(Si),E(VSi)) depending on the determined spatial deviations of the image data, wherein the error mask (E(Si), E(VSi)) indicates the error positions of image defects within the comparison image (Si,VSi).- Determine, in particular by estimation, local correction values for the image data of the reference image (Si,VSi), wherein each local correction value is assigned to a correction position within the reference image (Si,VSi), - Generate a corrected reference image (Si,cor,VSi,cor) by inserting the local correction values at the error positions of the reference image (Si,VSi) displayed by the error mask (E(Si),E(VSi)).