Camera Control System Power Reduction via Scene Change Tracking
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Solution Overview
Problem
Digital cameras in battery-powered devices, such as laptops and smartphones, face significant power consumption challenges due to continuous operation in teleconferencing applications, particularly in generating and updating camera control parameters like auto-focus, auto-exposure, and video stabilization, which typically rely on high-power central processing units (CPUs).
Innovation Solution
Shifting the workload from high-power CPUs to lower-power image signal processors (ISPs) for generating camera control parameters, using a simplified algorithm when scene changes are minimal, allowing the CPU to enter a power-conserving sleep state for extended periods, and utilizing a scene change tracker to determine when to switch between CPU and ISP processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the CPU generates camera control parameters using a complex processing algorithm, then the quality and accuracy of camera control (auto-focus, auto-exposure, video stabilization) is improved, but the power consumption increases significantly
Solution Approach 1:
The patent divides the processing workload into two segments: the CPU handles complex algorithm execution for high-accuracy camera control parameter generation, while the ISP handles preliminary image processing and data preparation. This segmentation allows each component to operate in its optimal performance range, with the CPU entering low-power states when full processing capability is not needed.
Solution Approach 2:
The system dynamically adjusts the processing mode between CPU and ISP based on scene change detection. When scene changes are detected, the CPU activates to provide high-accuracy processing; when no scene changes occur, the system switches to ISP-only mode to conserve power. This dynamic adaptation resolves the contradiction between maintaining accuracy and reducing power consumption.
2Speed
If the CPU operates continuously to generate camera control parameters, then the responsiveness and quality of camera control is improved, but the battery life decreases
Solution Approach 1:
The system implements periodic scene change detection using the ISP, which operates at low power. When no scene changes are detected for extended periods, the CPU enters low-power sleep states. This periodic monitoring approach maintains camera control responsiveness while significantly extending battery life compared to continuous CPU operation.
Solution Approach 2:
The ISP acts as an intermediary between the camera hardware and the CPU. It performs preliminary processing and scene change detection, allowing the CPU to remain in low-power states while still maintaining the capability to respond quickly when scene changes occur. This intermediary role resolves the contradiction between responsiveness and battery life.
3Use of energy by moving object
If a simplified processing algorithm is used in the ISP, then the power consumption is reduced, but the quality of camera control parameters may be compromised
Solution Approach 1:
The processing pipeline is segmented such that the ISP performs simplified preliminary processing and scene change detection, while the CPU handles the complex algorithms required for high-accuracy camera control parameter generation. This segmentation allows the ISP to operate with lower power consumption while maintaining overall system accuracy through CPU intervention when needed.
Solution Approach 2:
The system dynamically switches between ISP-only simplified processing and CPU-based complex processing based on scene change detection. When scene changes occur, the CPU activates to provide high-accuracy processing; otherwise, the simplified ISP processing suffices. This dynamic approach maintains accuracy when needed while reducing power consumption during stable scenes.
Data Source
AI summary
Techniques are provided for a camera control system with reduced power consumption. A system implementing the techniques according to an embodiment includes a scene change tracker configured to quantify a level of change between current and previous image frames provided by the camera. The system also includes a general purpose processor to generate camera control parameters using a first processing algorithm, based on the current and previous image frames, if the level of change exceeds a threshold. The system further includes an image signal processor to generate the camera control parameters using a second processing algorithm, based on the current and previous image frames, if the level of change is less than or equal to the threshold. The image signal processor consumes less power than the general purpose processor and the second processing algorithm is less computationally complex than the first processing algorithm.