Image Capture Exposure Timing Adjustment for Flicker Light Sources
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Solution Overview
Problem
Image capturing devices face exposure and color nonuniformity issues when using flicker light sources due to the periodic flicker of fluorescent lamps, leading to variations in exposure and color temperature among sequentially captured images.
Innovation Solution
An image capturing device with a photometric unit, operation unit, calculation unit, and adjustment unit that calculates light quantity change characteristics and adjusts exposure timing to mitigate the effects of flicker light sources, employing methods such as overall average detection or partial detection based on selected image capturing modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If image capture with a high shutter speed is performed under a flicker light source, then sensitivity improvement and bright image acquisition become possible, but exposure nonuniformity and color nonuniformity occur in the captured image
Solution Approach 1:
The system performs preliminary detection of the light quantity change characteristic of the illumination light before image capture. By detecting the flicker pattern in advance and calculating its period, the system can determine the optimal exposure timing in advance, ensuring that the exposure is performed when the light quantity is at a relative maximum, thus avoiding exposure nonuniformity while maintaining high shutter speed
Solution Approach 2:
The system changes the exposure timing parameter based on the detected light quantity change characteristic. By adjusting the exposure timing to coincide with the peak of the flicker cycle (determined through photometric detection and period calculation), the system optimizes the exposure moment to achieve uniform exposure across the image sensor while maintaining high shutter speed capability
2Speed
If image capture with a high shutter speed is performed under a flicker light source, then sensitivity improvement becomes possible, but variation in exposure and color temperature occurs among sequentially captured images
Solution Approach 1:
The system continuously monitors the light quantity change characteristic through the photometric unit and uses this feedback to adjust exposure timing for each captured image. By detecting the actual flicker pattern and using it to synchronize exposure timing across multiple sequential captures, the system ensures consistent exposure and color temperature while maintaining high shutter speed operation
Solution Approach 2:
Before each image capture in a sequence, the system performs preliminary detection of the light quantity change characteristic and calculates the optimal exposure timing based on the detected flicker period. This preliminary action ensures that each sequentially captured image is exposed at the optimal moment, maintaining consistency across the entire sequence
3Manufacturing precision
If exposure timing is adjusted based on light quantity change characteristic, then exposure nonuniformity is reduced, but additional processing steps are required to detect and calculate flicker characteristics
Solution Approach 1:
The photometric unit serves multiple functions: it not only performs standard photometry for exposure calculation but also detects the light quantity change characteristic for flicker detection. By reusing the same hardware component for dual purposes, the system achieves exposure uniformity improvement without adding significant processing complexity or additional hardware
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 solution effectively reduces exposure nonuniformity and color temperature variations by synchronizing exposure timing with the relative maximum light quantity of flicker light sources, ensuring consistent image quality across multiple frames.
Implementation Method 1
a photometric unit configured to obtain respective photometric values of a plurality of photometry areas in an image capturing area
Data Source
AI summary
Included are a photometric unit configured to obtain respective photometric values of a plurality of photometry areas in an image capturing area, an operation unit configured to perform setting regarding continuous shooting and/or focus adjustment, a calculation unit configured to calculate a light quantity change characteristic of a photometric target based on the photometric values of the plurality of photometry areas, an adjustment unit configured to adjust exposure timing based on the light quantity change characteristic, and a control unit configured to change a method of calculating the light quantity change characteristic according to the setting regarding continuous shooting and/or focus adjustment, and to determine whether the exposure timing is adjusted based on the light quantity change characteristic.