Flicker Detection Using DC-Free Difference Vectors and Square Wave Correlation
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Solution Overview
Problem
Existing methods for detecting flicker in image frames suffer from poor accuracy and are heavily influenced by motion, making them inefficient and unreliable, especially in environments with periodically changing lighting conditions.
Innovation Solution
A method and apparatus that calculate mean values of image frame rows, subtract direct current components to create DC-free difference vectors, and use square waves to determine the presence and frequency of flicker by analyzing dot products, effectively isolating flicker detection from image content and motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional flicker detection methods are used, then the detection process can be performed, but the detection accuracy is poor and motion has considerable influence
Solution Approach 1:
The patent extracts only the necessary information for flicker detection by calculating mean values of selected rows and creating DC-free difference vectors. This extraction process removes image content and motion-related information that would interfere with flicker detection, leaving only the temporal lighting variations that contain flicker signals.
Solution Approach 2:
The patent introduces square wave templates as intermediary elements to mediate between the raw image data and flicker detection. By correlating the DC-free difference vectors with square wave templates at different frequencies, the method transforms the complex flicker detection problem into a simpler pattern matching problem that is insensitive to motion and image content.
2Productivity
If subtraction of two image frames is performed to detect spatial sine wave, then flicker detection can be done with minimal image content, but image content is reduced which may lose information
Solution Approach 1:
The patent segments the image frame into selected rows and calculates mean values for each row, creating a simplified representation that retains temporal flicker information while reducing spatial detail. This segmentation allows efficient processing with fewer data points while maintaining the essential flicker detection capability.
Solution Approach 2:
The method extracts only the mean values of selected rows and subsequently creates DC-free difference vectors by subtracting consecutive frame representations. This extraction process removes redundant image content information while preserving the temporal variations that contain flicker signals, achieving efficient detection with minimal necessary data.
3Reliability
If mean values of selected rows are calculated and DC-free difference vectors are created, then motion influence is reduced, but calculation complexity increases
Solution Approach 1:
The patent segments the image processing task into distinct stages: calculating mean values of selected rows, creating DC-free difference vectors, and correlating with square wave templates. This segmentation of the calculation process makes the complexity manageable and allows each stage to be optimized independently while maintaining motion robustness.
Data Source
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AI summary
The present invention discloses a flicker detection method and a flicker detection apparatus. The method includes: calculating the mean values of selected rows of image frames to constitute a mean value vector; calculating a differential vector between the mean value vectors of a current frame and a previous frame; calculating a DC-free difference vector; building a first square wave and a second square wave, and a third square wave and a fourth square wave; calculating a first frequency reference value; calculating a second frequency reference value; and if the difference between the first and second frequency reference values is above a threshold, then it is determined that flicker is present in the current frame; otherwise, it is determined that no flicker is present.