Imaging Device Flash Band Correction via Rolling Shutter Signal Comparison
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Solution Overview
Problem
Existing methods for detecting and correcting flash bands in imaging devices, particularly in CMOS imaging elements using the rolling shutter method, face challenges such as misdetection when signal levels are clearly distinguished in an up-down direction, difficulty in detecting continuous flash bands, and potential video halts due to frame replacement corrections, especially in scenarios with multiple flashes or gradual signal level changes.
Innovation Solution
An imaging device with an optical system that disperses light, multiple imaging elements capturing images using a rolling shutter method, a comparison unit calculating level differences between image signals, and a correction unit addressing flash band influences by shifting the slit range between the imaging elements and applying correction values based on synchronized signal levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flash band detection is performed by comparing signal levels between lines in one frame, then flash bands can be detected, but subjects with clear signal level distinctions in the up-down direction are misdetected as flash bands
Solution Approach 1:
The patent transitions from detecting flash bands within a single frame to comparing signal levels across multiple frames. By shifting the detection dimension from horizontal (line-by-line within one frame) to temporal (frame-by-frame comparison), the system can distinguish between actual flash bands and natural vertical signal variations in subjects.
Solution Approach 2:
The system uses feedback from frame comparisons to identify and correct flash bands. By continuously monitoring signal level changes across frames and using this feedback information, the system can accurately detect flash bands while avoiding false detections from subjects with vertical signal gradients.
2Manufacturing precision
If frame replacement correction is used to remove flash bands, then flash bands can be corrected, but video halts occur when flash bands continue over several frames
Solution Approach 1:
The patent performs preliminary correction by fusing frames before the flash band effect fully develops. By detecting flash bands early and applying correction in advance through frame fusion, the system prevents video halts while maintaining correction quality.
Solution Approach 2:
Instead of replacing frames individually, the system merges multiple frames through fusion to create a corrected image. This combining approach maintains video continuity while achieving flash band correction, as the fused result smooths out the interruptions caused by sequential frame replacement.
3Adaptability or versatility
If multiple flashes are emitted all at once in the same frame, then multiple flash bands occur at different signal levels, but detection and correction become difficult
Solution Approach 1:
The patent segments the flash band detection into multiple levels by analyzing signal level differences across different frames. By breaking down the complex multi-level flash band pattern into comparable frame differences, the system can accurately detect and correct each flash band even when multiple flashes occur simultaneously.
4Adaptability or versatility
If flash lighting time lengthens, then flash bands occur with gradual signal level changes over tens to hundreds of lines, but accurate detection and correction become difficult
Solution Approach 1:
The patent addresses gradual flash bands by shifting detection to the temporal dimension (across frames) rather than relying solely on spatial line comparisons within a single frame. This allows the system to detect gradual changes that span tens to hundreds of lines by observing their progression across multiple frames.
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
Accurately detects and corrects flash bands, reducing misdetection and video halts, while effectively handling complex and gradual flash band changes, maintaining image quality and preventing noticeable flash band artifacts.
Implementation Method 1
an optical system configured to disperse light of a subject image
Implementation Method 2
a plurality of imaging elements configured to capture subject images dispersed by the optical system using a rolling shutter method
Data Source
AI summary
An imaging device includes an optical system, a plurality of imaging elements, an imaging unit, a comparison unit, and a correction unit. The optical system is configured to disperse light of a subject image. The imaging elements are configured to capture subject images dispersed by the optical system using a rolling shutter method. The imaging unit is configured to shift a slit range, which is between a front curtain and a rear curtain of the rolling shutter method, by at least one line in a sub-scanning direction between the plurality of imaging elements. The comparison unit is configured to calculate a level difference in units of lines between image signals output by the plurality of imaging elements by comparing signal levels of the image signals, and the correction unit configured to correct influence of a flash band on the image signals on the basis of the level difference.