CMOS Pixel Circuit Bi-Directional Scan for Flicker Artifact Reduction
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Solution Overview
Problem
Illuminant flicker, caused by varying light intensity from AC-powered sources, results in unwanted artifacts in images captured by CMOS image sensors, such as bands of differing brightness across images.
Innovation Solution
Operating pixel circuits in a bi-directional mode, where first information is acquired in forward row-sequential order and second information in reverse row-sequential order, and combining these samples to reduce flicker artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If pixel circuits operate in conventional row-sequential mode, then device complexity is low and ease of operation is high, but illuminant flicker causes bands of differing image brightness to appear across captured images
Solution Approach 1:
The patent segments the image acquisition process into multiple passes: a first pass acquiring image data in forward row-sequential order, and a second pass acquiring image data in reverse row-sequential order. By dividing the acquisition into segments taken at different times, the system captures variations caused by illuminant flicker across different rows, enabling subsequent cancellation of these variations through signal processing.
Solution Approach 2:
The patent implements periodic action by repeatedly acquiring image data in alternating forward and reverse passes. This periodic multi-pass acquisition strategy allows the system to sample the scene multiple times under varying illuminant conditions, capturing the temporal variations introduced by flicker and enabling their removal through differential processing.
2Object-affected harmful factors
If multiple passes are used to acquire image data in forward and reverse order, then flicker artifacts are reduced, but loss of time increases due to repeated scanning of pixel circuits
Solution Approach 1:
The patent maintains continuity of useful action by performing the second pass of image data acquisition immediately after the first pass, without interrupting the overall imaging process. The system continuously scans the pixel circuits in reverse order during the second pass, ensuring that the scene remains relatively stable between passes and that the useful action of light capture continues uninterrupted, minimizing temporal losses.
Data Source
AI summary
Methods for reducing artifacts caused by illuminant flicker are provided. One such method comprises: providing pixel circuits; and operating the pixel circuits in a bi-directional mode during which first information corresponding to a scene is acquired in forward row-sequential order of the pixel circuits and then second information corresponding to the scene is acquired in a reverse row-sequential order of the pixel circuits. Systems also are provided.