Dynamic Reconstruction Workload Allocation in Imaging Systems
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Solution Overview
Problem
Integrated-circuit image sensors face challenges in managing reconstruction workload and buffer memory requirements due to the inverse dependence on exposure time, leading to bandwidth limitations and increased memory needs, especially when exposure times are prolonged.
Innovation Solution
The imaging system dynamically allocates reconstruction workload between the sensor stack and the image signal processor, shifting operations based on exposure time to maintain data transfer bandwidth within the narrow signaling interface's capacity and limit sensor stack memory usage, using a configurable reconstruction logic to adjust workload allocation between the two components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If reconstruction operations are performed entirely on the sensor stack, then buffer memory requirements increase with prolonged exposure times, but if performed entirely on the image signal processor, then data transfer bandwidth requirements exceed the narrow signaling interface capacity
Solution Approach 1:
The patent divides the image reconstruction workload into two segments: buffer management operations are performed on the sensor stack, while actual image reconstruction operations are performed on the image signal processor. This segmentation allows the narrow bandwidth interface to transmit only essential buffer management data rather than all raw image data, resolving the bandwidth-memory contradiction.
Solution Approach 2:
The patent introduces an intermediary buffer management mechanism that operates on the sensor stack to pre-process and manage image data before transmission. This intermediary layer reduces the data volume requiring transmission over the narrow bandwidth interface while maintaining the ability to handle prolonged exposure times through efficient buffer management.
2Power
If the signaling interface bandwidth is increased to handle all raw data transfer, then data transfer capacity improves, but device complexity and cost increase
Solution Approach 1:
The patent applies partial action by transmitting only the necessary buffer management data rather than all raw image data through the signaling interface. This partial data transmission approach maintains adequate bandwidth utilization without requiring an excessively complex high-bandwidth interface, thus resolving the contradiction between bandwidth and complexity.
3Duration of action of moving object
If buffer memory capacity on the sensor stack is increased to handle prolonged exposure times, then exposure time flexibility improves, but sensor stack memory costs and area increase
Solution Approach 1:
The patent implements preliminary action by performing buffer management operations on the sensor stack before data transmission. This allows the system to prepare and manage buffer data efficiently with minimal memory capacity, while the actual reconstruction is deferred to the image signal processor, thus achieving prolonged exposure time flexibility without requiring large sensor stack memory.
Data Source
AI summary
Multiple image data subframes corresponding to respective portions of an exposure interval are generated within a sensor device of an image system. Depending on whether the exposure interval exceeds one or more exposure time thresholds, data representative multiple image data subframes are output from the image sensor device in one of at least two formats, including a first format in which each of the subframes of image data is output in its entirety, and a second format in which a logical combination of at least two of the subframes of image data is output instead of the at least two of the subframes of image data such that the total volume of image data output from the image sensor device is reduced relative to the first format.