Flicker Compensation Device for Moving Subjects
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Solution Overview
Problem
Conventional flicker correction methods are ineffective in detecting and correcting flicker in images captured by imaging elements under AC-powered illumination, especially when the subject is moving or when determining the presence of flicker takes a long time, due to the need for averaging values over multiple field periods.
Innovation Solution
A flicker correction device and method that calculates line average values, detects movement, and extracts flicker frequency by dividing recent line average values by stored values, allowing for rapid determination of flicker presence and correction, even when the field period is slightly deviated from the flicker period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If line average values are stored in memory for each one third phase of the period between subsequent coincidences between the field period and the flicker period, then flicker correction can be performed, but when the subject is moving, a correct reference value cannot be calculated and flicker cannot be detected
Solution Approach 1:
The patent applies dynamics by making the flicker correction system adaptive to moving subjects. Instead of using a fixed reference value that assumes stationary subjects, the system dynamically adjusts by detecting subject movement and switching to a different correction approach. The movement detection section compares line average values between current and previous fields to identify subject movement, and when movement is detected, the system suppresses flicker correction to avoid incorrect corrections on moving subjects.
Solution Approach 2:
The patent implements feedback through the movement detection mechanism. The system continuously monitors changes in line average values between current and previous fields, uses this feedback to determine whether the subject is moving, and adjusts the flicker correction process accordingly. This closed-loop feedback ensures that flicker correction is only applied when appropriate, maintaining reliability for stationary subjects while adapting to moving subjects.
2Reliability
If a reference value is created by averaging three average values delayed by 167, 334, and 500 field periods, then flicker correction can be performed, but it takes at least 500 field periods or longer until whether flicker exists or not is determined for the first time
Solution Approach 1:
The patent applies preliminary action by performing movement detection and flicker determination much earlier in the process than the conventional method. Instead of waiting 500 field periods to accumulate enough data for flicker determination, the system performs preliminary movement detection on a per-field basis and can determine flicker presence much sooner. This allows the system to start flicker correction much earlier while maintaining accuracy.
Solution Approach 2:
The patent segments the flicker detection process into smaller, more frequent steps. Rather than requiring a complete 500-field period cycle to determine flicker presence, the system divides the detection into incremental steps that can be performed on each field, allowing for much faster overall detection and correction while maintaining the same level of accuracy through the segmented approach.
3Object-affected harmful factors
If flicker correction is performed by averaging line average values over multiple field periods, then flicker can be reduced, but the correction process becomes complex and requires large memory capacity
Solution Approach 1:
The patent extracts only the essential information needed for flicker correction by focusing on line average values and their changes between fields. Instead of storing and processing complete image data or complex multi-phase reference values, the system extracts and processes only the necessary average value differences. This extraction approach maintains effective flicker correction while dramatically reducing memory requirements and computational complexity.
Data Source
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AI summary
An average value calculation section 100 calculates an average value of each line during the validity period of an input image signal. A three-field average value calculation section 104 calculates a 50 Hz flicker signal from which the light and shade of a subject is removed. A difference value calculation section 105 subtracts an n-field preceding field line average value from the line average value of the present frame. Then, a 60 Hz flicker signal, from which the light and shade of the subject is removed, is calculated by dividing the difference value by the line average value of the present frame. A flicker determination section 112 determines whether flicker exists or not, and whether the flicker frequency is 50 Hz or 60 Hz, on the basis of the extraction results of the 50 Hz flicker component extraction section 108, and of the 60 Hz flicker component extraction section 109.