Vehicle ToF Camera Exposure Control for Backlit and Low-Light Scenes

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Solution Overview

Problem

Autonomous vehicle navigation faces challenges in image capture and analysis due to imbalanced light distribution and insufficient lighting, making it difficult to set a global shutter speed for entire image sensors, especially in environments like backlit or low-light conditions.

Innovation Solution

A time-of-flight camera system with an exposure controller that determines individual pixel or region exposures based on distance information from sensors like LiDAR, RADAR, or ultrasonic sensors, and a high-definition map, allowing for varying exposure start times and durations to optimize light integration for each pixel region.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a global shutter speed is set for the entire image sensor, then the device complexity is reduced, but the image quality deteriorates in backlit or low-light conditions due to imbalanced light distribution

Engineering Contradiction:

Improveshutter control complexityVSAvoidimage capture accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The image sensor is divided into multiple pixel regions, each with its own exposure control. The exposure controller determines different exposure durations or start times for different pixel regions based on local lighting conditions, allowing each region to be optimized independently while maintaining overall system functionality

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different exposure parameters are applied to different pixel regions based on their specific lighting conditions. The exposure controller adjusts exposure duration or start time for each pixel region individually, enabling local optimization of image quality in backlit or low-light conditions without requiring complex global shutter control

Inventive Principle:

Principle #3Local quality

2Reliability

If individual pixel regions use different exposure durations or start times, then the image quality improves in varying lighting conditions, but the device complexity increases

Engineering Contradiction:

Improveimage capture accuracyVSAvoidexposure control complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The exposure controller automatically determines appropriate exposure parameters for each pixel region based on distance information from sensors (LiDAR, RADAR, ultrasonic) and high-definition map data. This self-adjusting mechanism eliminates the need for manual intervention or complex external control systems, reducing overall device complexity while maintaining individualized exposure control

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system uses feedback from distance sensors and map data to dynamically adjust exposure parameters for each pixel region. The exposure controller continuously monitors environmental conditions and modifies exposure settings accordingly, enabling adaptive illumination control that simplifies the overall system architecture

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances camera performance in autonomous driving by ensuring accurate image capture in poor lighting conditions, preventing under or over exposure across different regions of the image.

Implementation Method 1

Each pixel region begins to integrate incident light starting at the corresponding exposure start time and continues to integrate light for the corresponding exposure duration

Methodology Applied

Scientific EffectLight integration: Absorption (EM radiation)

Implementation Method 2

A time-of-flight camera system with an exposure controller that determines individual pixel or region exposures based on distance information

Methodology Applied

Scientific EffectTime of flight: Time of Flight

Data Source

PatentUS11877066B2Adaptive illumination for a time-of-flight camera on a vehicle

Publication Date: 2024.01.16 CREATEAI INC

AI summary

Disclosed are devices, systems and methods for capturing an image. In one aspect an electronic camera apparatus includes an image sensor with a plurality of pixel regions. The apparatus further includes an exposure controller. The exposure controller determines, for each of the plurality of pixel regions, a corresponding exposure duration and a corresponding exposure start time. Each pixel region begins to integrate incident light starting at the corresponding exposure start time and continues to integrate light for the corresponding exposure duration. In some example embodiments, at least two of the corresponding exposure durations or at least two of the corresponding exposure start times are different in the image.