Time-of-flight sensor exposure estimation
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Solution Overview
Problem
Current imaging systems face delays in capturing images of fast-moving or dynamic scenes due to the time required for automatic exposure control, especially when using flash, which can result in missed moments and inefficiencies in autofocus and exposure determination.
Innovation Solution
The integration of a time-of-flight (TOF) sensor to quickly determine the distance and reflectance of a target object, allowing for faster exposure adjustment and reduced latency in image capture by using pre-flash and main flash exposure calculations based on TOF data, thereby streamlining the exposure determination process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional automatic exposure control is used to determine proper exposure settings, then accurate exposure can be achieved, but the system experiences delays and may miss fast-moving scenes
Solution Approach 1:
The system performs preliminary actions by using the TOF sensor to pre-determine distance and reflectance information before the actual image capture. This preliminary data is then used to calculate the required flash exposure level, allowing the imaging system to skip the traditional time-consuming pre-flash exposure step and directly apply the calculated exposure settings, thus reducing overall exposure determination time while maintaining accuracy
Solution Approach 2:
The TOF sensor acts as an intermediary device that provides distance and reflectance measurements to the imaging system. This intermediary information serves as a substitute for the traditional pre-flash exposure method, enabling the system to calculate flash exposure levels more quickly by using the TOF-derived reflectance data in conjunction with the measured distance
2Measurement precision
If pre-flash exposure is performed to determine proper flash exposure level, then accurate flash exposure can be achieved, but the overall image capture time increases
Solution Approach 1:
The system replaces the mechanical/optical pre-flash exposure mechanism with a computational approach using TOF sensor data. Instead of physically performing a pre-flash exposure to measure reflectance, the system uses the TOF sensor's time-of-flight measurements to calculate reflectance and determine the required flash exposure level through computation, thereby eliminating the time-consuming pre-flash step while maintaining exposure accuracy
Solution Approach 2:
The system changes the parameters used for exposure determination by relying on TOF-measured distance and reflectance values instead of relying solely on pre-flash exposure measurements. By using the formula that incorporates TOF-derived reflectance and distance parameters, the system can directly calculate the appropriate flash exposure level without performing the traditional pre-flash exposure sequence
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
This approach significantly reduces the time needed for exposure adjustment and autofocus, enabling faster and more reliable image capture of dynamic scenes without the user needing to anticipate the moment, thus minimizing missed shots and improving overall imaging system efficiency.
Implementation Method 1
information from a time-of-flight sensor used to determine a distance to, and a reflectance of, a target object
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
This application relates to capturing an image of a target object using information from a time-of-flight sensor. In one aspect, a method may include a time-of-flight (TOF) system configured to emit light and sense a reflection of the emitted light and may determine a return energy based on the reflection of the emitted light. The method may measure a time between when the light is emitted and when the reflection is sensed and may determine a distance between the target object and the TOF system based on that time. The method may also identify a reflectance of the target object based on the return energy and may determine an exposure level based on a distance between the target object and a reflectance of the target object.