Flicker Detection in Image Sensors Using Multi-Frame Analysis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image capturing apparatuses struggle to effectively detect and reduce flicker caused by light sources like fluorescent lamps and LEDs, leading to exposure and color unevenness in images.
Innovation Solution
The apparatus employs a method to detect flicker by analyzing light amount change frequencies at multiple imaging cycles, allowing for the selection of an optimal shutter speed to minimize the effect of flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high shutter speed is used to capture bright images with less blur, then image brightness and sharpness are improved, but exposure unevenness and color unevenness occur due to flicker from light sources
Solution Approach 1:
The system performs preliminary flicker detection by capturing a detection image at a first shutter speed before capturing the main image. Based on the detected flicker characteristics (frequency and amplitude), it pre-adjusts the shutter speed to a second speed that minimizes flicker effects, thereby preventing exposure unevenness before it occurs.
Solution Approach 2:
The system changes the shutter speed parameter dynamically based on detected flicker conditions. When flicker is detected, it adjusts the shutter speed to a value that is not synchronized with the flicker frequency, thereby eliminating exposure unevenness while maintaining image brightness.
2Shape
If shutter speed is increased to reduce object blur, then image sharpness is improved, but flicker detection accuracy deteriorates due to insufficient light capture
Solution Approach 1:
The imaging process is segmented into two distinct phases: a flicker detection phase using a slower shutter speed to accurately measure light fluctuations, and a main image capture phase using an optimized shutter speed. This segmentation allows each phase to use appropriate parameters for its specific purpose without compromise.
Solution Approach 2:
The system performs periodic flicker detection by capturing detection images at specific intervals before main image capture. This periodic measurement allows accurate characterization of the light source's flicker behavior, which then informs the selection of optimal shutter speed parameters.
3Device complexity
If detection is performed at a single shutter speed, then the detection process is simple, but flicker detection coverage is limited to specific frequencies
Solution Approach 1:
The system dynamically selects the optimal shutter speed for main image capture based on the flicker characteristics detected from the detection image. This dynamic adjustment allows the system to adapt to different flicker frequencies (including LED flicker that may not be integer multiples of power frequency) while maintaining a relatively simple detection process.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An image capturing apparatus includes driving control means configured to control driving of an image sensor, and flicker detection means configured to detect flicker, which is a periodic change in a light amount of an object, based on a signal output from the image sensor, wherein the driving control means is configured to, if the image sensor outputs a flicker detection signal to be used in detecting the flicker, control the driving of the image sensor at n different frame rates, n being a natural number greater than or equal to 3, wherein a least common multiple of the n frame rates used in detecting the flicker is not same as any of the n frame rates, and wherein the flicker detection means is configured to detect the flicker based on the flicker detection signal obtained at each of the n frame rates.