DOL WDR Sensor Image Processing with Dynamic Buffer Partitioning
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Solution Overview
Problem
Current wide dynamic range (WDR) sensors, especially digital overlap (DOL) sensors, face challenges with high dual data rate (DDR) memory bandwidth requirements and motion artifacts, which are costly and difficult to correct, and are not ideal for control applications, particularly when multiple sensors are used in automotive and surveillance systems.
Innovation Solution
The integration of an image sensor processor (ISP) circuit that efficiently manages pixel data from multiple DOL WDR sensors by using DDR memory for longest exposure data and dedicated buffers for shorter exposure data, merging pixel data through a motion adaptive merge circuit, and processing it with an image pipeline circuit to reduce DDR memory bandwidth requirements and enhance image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If digital overlap (DOL) sensors are used to reduce cost and motion artifacts, then manufacturing cost and image quality are improved, but DDR memory bandwidth requirements increase
Solution Approach 1:
The patent divides the buffer memory into multiple segments or buffers, where each buffer stores data from a specific exposure. This segmentation allows parallel processing of multiple exposures without requiring all data to be simultaneously available in a single large buffer, thereby reducing the peak DDR memory bandwidth requirements while maintaining the DOL sensor's cost and quality advantages.
Solution Approach 2:
The patent implements preliminary buffering of exposure data in on-chip memory before transferring to DDR memory. By pre-organizing and temporarily storing the multi-exposure data locally, the system reduces the frequency and volume of DDR memory accesses, thereby lowering bandwidth requirements while preserving the benefits of DOL sensors.
2Reliability
If multiple DOL WDR sensors are used in control applications, then imaging coverage and reliability are improved, but DDR memory bandwidth limitations are exacerbated
Solution Approach 1:
The patent merges data from multiple DOL WDR sensors through a unified processing architecture that combines their respective exposure buffers. By integrating multiple sensor inputs into a coordinated buffer management system, the patent achieves improved reliability and coverage for control applications while optimizing DDR memory bandwidth usage through shared buffer resources and synchronized data flow.
Solution Approach 2:
The patent creates a universal buffer management architecture that can handle data from any number of DOL WDR sensors using the same buffer structures and processing logic. This multi-functional design allows the system to scale to multiple sensors without proportionally increasing DDR bandwidth requirements, as the buffer architecture serves multiple sensors simultaneously.
3Device complexity
If DDR memory is shared for multiple tasks, then device complexity is reduced, but access time limitations are not ideal for control applications
Solution Approach 1:
The patent implements local buffering on-chip for each sensor and exposure, providing fast local access to recently captured data. This local quality enhancement allows critical processing operations to access buffer data quickly without relying on slower shared DDR memory, thereby reducing access time penalties while maintaining a relatively simple shared memory architecture for long-term storage.
Data Source
AI summary
Methods and integrated circuits to process image data from single or multiple digital overlap (DOL) wide dynamic range (WDR) sensors, in which first received pixel data associated with a first exposure of a sensor image is stored in a DDR memory circuit, second received pixel data associated with a second exposure of the image is stored in the first buffer, third received pixel data associated with a third exposure of the image is stored in a second buffer, and fourth received pixel data associated with a fourth exposure of the image is provided to a merge circuit, and merged pixel data is stored in a dynamically partitioned line buffer for processing by an image pipeline circuit to facilitate interfacing multiple DOL WDR sensors in an interleaved fashion.