CMOS Global Shutter Light Leakage Correction via Dual Readout
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The global shutter method in CMOS image sensors experiences light leakage phenomena, leading to image quality deterioration due to charge leakage during readout, particularly in high luminance subjects.
Innovation Solution
A photographing apparatus and method that perform a first and second readout of charges from pixels, with an image processor detecting light leakage by comparing readout values and applying corrections to generate an improved image, using a threshold-based approach to identify and correct light leakage pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a global shutter is used to capture images, then all pixels can simultaneously store photo-generated charges, but light leakage occurs during the readout process causing image quality deterioration
Solution Approach 1:
The patent performs a first readout of charges from pixels before the light leakage becomes severe, then performs a second readout after the full exposure period. By preliminarily reading out charges early in the exposure sequence, the system captures valid charge data before leakage contaminates the signal, thus preserving image quality while maintaining global shutter functionality
Solution Approach 2:
The image processor compares the first readout values with the second readout values to detect light leakage. When leakage is detected in the second readout, the system uses the first readout data as a reference to correct or replace the corrupted pixel values, creating a feedback mechanism that maintains image quality despite the inherent light leakage problem
2Adaptability or versatility
If charges are stored in pixel-level storages for extended periods, then global shutter operation is enabled, but light leakage increases in proportion to the readout period
Solution Approach 1:
The system performs a preliminary first readout of charges from pixels at an earlier time point during the exposure sequence. This preliminary action captures charge data before the leakage accumulates to problematic levels, allowing the system to maintain global shutter operation while obtaining clean signal data from the preliminary readout
Solution Approach 2:
When light leakage is detected in the second readout, the system discards the corrupted pixel values from the second readout and recovers the valid image information from the first readout. This discarding and recovering approach eliminates the harmful leakage effect while preserving the useful charge data captured earlier
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
This solution effectively detects and corrects light leakage, thereby improving image quality by accurately identifying affected pixels and adjusting their values to mitigate charge leakage effects.
Implementation Method 1
image sensors that electrically convert light received into a lens of a photographing apparatus
Data Source
AI summary
An photographing apparatus includes: an image sensor that includes a plurality of pixels and is configured to perform a first readout on charges stored in a group of pixels among the plurality of pixels at a first readout time and perform a second readout on charges stored in the plurality of pixels, including the group of pixels, at a second readout time; and an image processor configured to detect a pixel in which a light leakage has occurred of among the plurality of pixels based on at least one of a value the first readout charges and a value of the second read out charges, and perform a correction on the detected pixel to generate an image.