Camera Flicker Detection via Light Sampling
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Solution Overview
Problem
Fluorescent lamps' flicker, caused by alternating current power frequency, can result in artifacts in video images, complicating the challenge of reducing undesirable flicker artifacts as different regions use 50 Hz and 60 Hz AC frequencies, requiring cameras to synchronize exposure timings with varying frequencies.
Innovation Solution
A camera system with a light detector circuit and processing capabilities to automatically detect and adjust exposure timings based on ambient light intensity variations, using a method that involves sampling light intensity and analyzing scalar product outputs to identify periodic flicker frequencies, allowing for automatic adaptation to different AC power frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the camera uses fixed exposure timings matched to a specific AC frequency, then flicker artifacts are reduced for that frequency, but the camera cannot operate correctly in regions with different AC frequencies
Solution Approach 1:
The camera performs preliminary detection of the AC power frequency by analyzing light intensity variations from ambient lighting before capturing the main image. This preliminary action allows the camera to identify the local frequency (50Hz or 60Hz) and adjust exposure timings in advance, ensuring optimal flicker artifact reduction for the specific region without requiring manual user configuration.
Solution Approach 2:
The camera dynamically adjusts its exposure timings based on the detected AC frequency. Rather than using fixed exposure settings, the system modifies its operational parameters in real-time according to the ambient lighting conditions and detected frequency, enabling it to adapt to different AC power frequencies across various regions while maintaining reliable flicker artifact reduction.
2Reliability
If the camera provides manual frequency configuration options, then users can select the correct AC frequency, but this increases device complexity and requires user knowledge
Solution Approach 1:
The camera system performs self-service by automatically detecting the local AC power frequency through analysis of light intensity variations from ambient fluorescent or LED lighting. The system extracts frequency information from the periodic variations in light intensity and automatically configures its exposure timings accordingly, eliminating the need for manual user configuration and simplifying the device interface while maintaining reliable frequency matching.
3Ease of operation
If the camera automatically detects AC frequency, then user configuration is eliminated, but processing time and computational resources increase
Solution Approach 1:
The camera performs partial frequency detection by analyzing only the necessary portion of the light intensity signal required to determine the AC frequency. Rather than processing the entire signal spectrum, the system focuses on detecting the characteristic periodic variations in light intensity that correspond to 50Hz or 60Hz frequencies, enabling automatic frequency detection with minimal processing time and computational overhead.
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
The camera system effectively reduces flicker artifacts by synchronizing exposure timings with the detected AC power frequency, eliminating the need for user configuration and allowing operation in different environments, thereby improving image quality.
Implementation Method 1
a photo-sensitive transistor, a modulator and a logic unit. The photo-sensitive transistor generates electric signals responsive to light incidents thereon
Data Source
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AI summary
One disclosed embodiment includes detecting flicker in a photographic setting by introducing a camera into the setting so that light is incident upon the camera. A plurality of samples are captured from a light detector circuit of the camera, each of which is dependent upon intensity of light incident upon the camera. The method further includes processing the samples to identify whether the incident light is varying in intensity at one or more pre-selected frequencies. The processing may include multiplying the samples with one or more periodic signals to generate scalar product outputs, and analyzing the scalar product outputs to ascertain the presence of periodic flicker.