Multi-Camera Master AE/AWB Sharing for Synchronized Low-Power Imaging
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Solution Overview
Problem
Existing multi-camera systems in smart vehicles face challenges in efficiently operating multiple cameras with low power consumption and low cost, particularly in dynamic illumination environments, while maintaining synchronized outputs.
Innovation Solution
A method for operating a multi-camera system where a first auto exposure and auto white balance are performed on a master camera, with results applied to all cameras, and operation modes adjusted based on illumination changes to optimize power usage and cost, including synchronization of outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If auto exposure and auto white balance are performed on every camera every frame, then image quality is maintained, but power consumption increases
Solution Approach 1:
The system segments the multi-camera operation into master camera and slave camera groups. Only the master camera performs auto exposure and auto white balance operations, while slave cameras reuse the master's results. This segmentation reduces the total number of computations from N cameras to 1 camera, significantly lowering power consumption while maintaining image quality across all cameras.
Solution Approach 2:
The master camera serves multiple functions: it performs auto exposure and auto white balance for itself and simultaneously provides these calibration results to all slave cameras. This multi-functionality eliminates redundant operations and reduces overall system power consumption while maintaining consistent image quality across all cameras.
2Productivity
If multiple independent image signal processors are used for each camera, then processing capability is improved, but system cost increases
Solution Approach 1:
The system merges multiple camera processing functions into a single image signal processor. The ISP processes images from all cameras centrally, applying auto exposure and auto white balance results from the master camera to slave camera images. This consolidation reduces the number of expensive ISP components needed while maintaining adequate processing capability for the multi-camera system.
Solution Approach 2:
Instead of having each camera perform independent auto exposure and auto white balance computations, the system creates and reuses calibration result copies from the master camera across all slave cameras. This copying approach eliminates redundant processing operations and reduces the computational burden on individual cameras, allowing for more cost-effective hardware configurations.
3Adaptability or versatility
If auto exposure and auto white balance are performed frequently, then adaptation to illumination changes is improved, but power consumption increases
Solution Approach 1:
The system implements feedback mechanisms to detect illumination environment changes and dynamically adjusts the frequency of auto exposure and auto white balance operations. When illumination changes are detected, the system increases the frequency of these operations on the master camera. When illumination is stable, the system reduces frequency, thereby adapting to environmental conditions while optimizing power consumption.
Solution Approach 2:
The system dynamically adjusts the operation frequency of auto exposure and auto white balance based on real-time illumination conditions. Rather than performing these operations at a fixed high frequency, the system modulates the frequency according to actual environmental needs, achieving adaptability to illumination changes while minimizing unnecessary power consumption during stable conditions.
Data Source
AI summary
In a method of operating a multi-camera system, a first auto exposure (AE) is performed on a first master camera among a plurality of first cameras controlled by a first image signal processor. A first auto white balance (AWB) is performed on the first master camera. Operations of all of the plurality of first cameras are controlled by the first image signal processor based on results of the first auto exposure and the first auto white balance.