Camera HDR Pre-Flash Segmentation for Exposure Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing camera systems face challenges in accurately determining exposure settings due to the pre-flash often resulting in under-exposed far objects and over-exposed close objects, making it difficult to estimate proper camera settings for image acquisition.
Innovation Solution
The use of High Dynamic Range (HDR) imaging during the pre-flash phase to generate a pre-flash image, which allows for accurate determination of camera settings such as exposure times and gain settings, reducing the risk of under or over exposure, and enabling the camera to configure settings for optimal image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a brief pre-flash is used to minimize power consumption and enrich user experience, then power consumption is reduced and user experience is improved, but exposure accuracy deteriorates causing under-exposed far objects and over-exposed close objects
Solution Approach 1:
The pre-flash is divided into multiple segments with different durations and intensities. Instead of using a single brief pre-flash, the system employs a first pre-flash with a first duration and intensity, followed by a second pre-flash with a second duration and intensity. This segmentation allows the system to gather sufficient light information for accurate exposure estimation while keeping each individual pre-flash brief enough to maintain low power consumption and good user experience.
Solution Approach 2:
The system dynamically changes pre-flash parameters (duration and intensity) based on scene requirements. By adjusting the duration and intensity of different pre-flash segments, the system can adapt to various lighting conditions and object distances, ensuring accurate exposure estimation without consistently using high-power long-duration pre-flashes. This parameter optimization resolves the contradiction between power consumption and measurement precision.
2Productivity
If a single temporary image is captured using pre-flash data, then the process is simple and fast, but the reliability of exposure setting determination deteriorates due to under-exposed far objects and over-exposed close objects
Solution Approach 1:
The single temporary image capture process is segmented into multiple capture stages. The system captures a first temporary image using a first pre-flash and then captures a second temporary image using a second pre-flash with different parameters. By combining information from multiple segmented captures, the system achieves reliable exposure setting determination while maintaining relatively fast acquisition speed, as each individual capture remains brief.
Solution Approach 2:
The system performs preliminary actions by capturing multiple temporary images with different pre-flash parameters before final image acquisition. This preliminary multi-stage capture process provides redundant information that improves the reliability of exposure setting determination. The preliminary captures are processed to estimate proper exposure settings, ensuring that the final image will be correctly exposed despite the brevity of individual pre-flashes.
3Measurement precision
If pre-flash duration is extended to improve exposure estimation accuracy, then measurement precision improves, but power consumption increases and user experience deteriorates
Solution Approach 1:
The system optimizes pre-flash parameters by implementing multiple pre-flash segments with progressively adjusted durations and intensities. The first pre-flash uses moderate parameters for initial exposure estimation, and the second pre-flash uses different parameters to refine the estimation. This parameter optimization ensures that the total power consumption remains acceptable while achieving sufficient measurement precision for accurate exposure settings.
Solution Approach 2:
The extended pre-flash duration is segmented into multiple shorter pulses rather than using one continuous long pre-flash. This segmentation reduces peak power consumption and improves user experience by providing brief light pulses, while the cumulative effect of multiple segments achieves the necessary exposure estimation accuracy. Each segment contributes to the overall measurement without requiring the system to sustain high power for an extended continuous period.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
An electronic device is described. The electronic device includes a flash configured to generate a pre-flash and a regular flash and a camera. The electronic device also includes a processor communicatively coupled to the flash and the camera. The processor is configured to, in response to receiving a picture request: determine one or more high dynamic range (HDR) settings and configure an HDR mode of the camera with the determined HDR settings; cause the flash to generate a pre-flash while the HDR mode of the camera is configured with the determined HDR settings; obtain an HDR image from the camera after causing the flash to generate the pre-flash and while the camera is configured with the determined HDR setting; and determine one or more camera configuration settings based on the obtained HDR image.