Camera Clock Calibration via Flicker Synchronization
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Solution Overview
Problem
Digital devices like CMOS image sensors experience non-uniform exposure of consecutive images due to imperfect matching between clock frequencies and illumination frequencies, leading to flickering effects in image display and negatively impacting image analysis algorithms.
Innovation Solution
A method that synchronizes the clock rate of a device's circuitry with the frequency of illumination modulation by adjusting the pixel integration time, using image intensity variability values to determine the optimal clock rate, thereby mitigating flickering phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clock rate is not synchronized with illumination frequency, then the image capture process is simple and fast, but flickering occurs and image quality deteriorates
Solution Approach 1:
The patent adjusts the pixel integration time parameter to be an integer multiple of the illumination cycle period. By changing the integration time from a fixed value to a dynamically adjusted value that satisfies the synchronization condition, the system eliminates flickering while maintaining operational simplicity. The controller modifies the integration time parameter based on detected illumination frequency, ensuring consistent image quality without complex hardware modifications.
2Reliability
If high-accuracy clocks are used to synchronize with illumination frequency, then flickering is reduced, but device cost and complexity increase
Solution Approach 1:
The system uses the illumination signal itself to determine the synchronization parameter. The controller detects the illumination frequency from the captured images and automatically adjusts the pixel integration time to match the illumination cycle. This self-adjusting mechanism eliminates the need for external high-accuracy clock sources or complex synchronization hardware, reducing device complexity while effectively mitigating flicker.
Solution Approach 2:
The patent implements a feedback loop where the controller continuously monitors image intensity variability and adjusts the pixel integration time accordingly. By measuring the flicker level in captured images and modifying the integration time to minimize variability, the system achieves automatic synchronization without requiring precise external clock references, thereby reducing hardware complexity while maintaining reliable flicker mitigation.
Data Source
AI summary
A method operable by circuitry including an image processor, an image sensor, and another clock-dependent device, including measuring a flicker using the image sensor, adjusting a clock rate of the circuitry according to the measured flicker, and operating the clock-dependent device using the adjusted clock rate.