Camera Shutter Lag Adjustment for PWM Lighting
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Solution Overview
Problem
LED lighting's use of pulse-width modulation (PWM) for dimming poses challenges for digital image capture due to variations in light intensity, limiting shutter speed and making it difficult to capture high-quality images, especially in conditions requiring fast shutter speeds like sports photography.
Innovation Solution
A camera system adjusts its shutter lag based on a PWM timing model to predict ambient light levels, ensuring exposure occurs at a selected light output level, thereby stabilizing image capture under PWM-controlled lighting conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If PWM dimming is used to control LED light intensity, then energy efficiency and flexibility are improved, but image capture quality deteriorates due to light intensity variations
Solution Approach 1:
The system performs preliminary actions by collecting ambient light data and creating a PWM timing model before image capture. This allows the camera to predict future light levels and calculate appropriate shutter lag values in advance, ensuring the shutter opens at optimal moments when light intensity is suitable for capture.
Solution Approach 2:
The system dynamically adjusts the shutter lag value based on real-time ambient light conditions and the PWM timing model. Instead of using a fixed shutter speed, the camera continuously calculates and updates the shutter lag to match the pulsing light pattern, allowing adaptive optimization of image capture quality under varying PWM conditions.
2Speed
If high shutter speed is used to freeze subject motion, then motion capture quality is improved, but image capture becomes impossible under PWM lighting due to light intensity variations
Solution Approach 1:
The system creates a PWM timing model in advance that predicts when light levels will be optimal for capture. This preliminary modeling allows the camera to plan shutter timing strategically, opening the shutter at moments when PWM lighting provides sufficient and stable illumination, even when using relatively fast shutter speeds to freeze motion.
Solution Approach 2:
The system continuously monitors ambient light levels and uses this feedback to update the PWM timing model and recalculate shutter lag values. This closed-loop approach ensures that the camera adapts to changes in PWM lighting conditions, maintaining reliable image capture even when using high shutter speeds for motion freezing.
3Reliability
If shutter speed is limited to match PWM cycling, then image capture reliability is improved, but productivity and capture flexibility deteriorate
Solution Approach 1:
By creating a comprehensive PWM timing model in advance that maps out light intensity patterns over time, the system enables photographers to plan and execute captures at optimal moments without being constrained by the PWM cycling frequency. The preliminary model provides a roadmap for reliable capture timing while maintaining flexibility in subject selection and composition.
Data Source
AI summary
An approach is provided to adjust a camera shutter lag. In the approach, data is collected that corresponds to an ambient light found in a physical environment with the ambient light being controlled using a pulse-width modulation (PWM). The pulse-width modulation corresponds to a PWM timing model. When an exposure request is received, the camera shutter lag is calculated using the PWM timing model. The calculated shutter lag is based on a future point in time at which the ambient light of the physical environment is predicted to be at a selected light output level, such as a power level selected by the user of a camera. When the calculated camera shutter lag has expired, a shutter of the camera is opened causing a camera lens to be exposed that results in a captured exposure.