Illumination-Invariant Road Marking Detection via Log Chromaticity

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Solution Overview

Problem

Current computer vision systems face challenges in accurately identifying painted road markings due to variations in illumination, which affect the accuracy of image processing and analysis in automotive driver-assistance devices.

Innovation Solution

A method and system that transform image data into illumination-invariant representations using a log chromaticity plane, oriented according to a bi-illuminant dichromatic reflection model, to isolate and enhance the detection of road markings by separating illumination and material aspects in road images.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If standard image processing is used to identify road markings, then the system is simple to implement, but accuracy deteriorates under varying illumination conditions

Engineering Contradiction:
Improveroad marking identification accuracyVSAvoidimage processing complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent transforms image data from standard RGB color space to log chromaticity space, changing the parameter representation to be illumination-invariant. This allows road marking colors to be consistently identified regardless of lighting conditions, resolving the contradiction between accuracy and complexity by using a mathematical transformation rather than complex hardware or algorithms

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a log chromaticity plane as an intermediary representation between the raw image and the road marking detection algorithm. This intermediate space separates illumination effects from material color information, allowing accurate marking identification without requiring complex illumination modeling or correction

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If illumination-invariant processing is implemented, then road marking identification accuracy improves, but computational complexity increases

Engineering Contradiction:
Improveroad marking detection accuracyVSAvoidcomputational processing power
Core Design Contradiction:
Measurement precisionVSPower

Solution Approach 1:

The patent applies logarithmic transformation to convert multiplicative illumination effects into additive components in the log chromaticity space. This mathematical parameter change simplifies the computational burden by allowing linear separation of illumination and material properties, reducing the processing power required compared to iterative or model-based illumination correction methods

Inventive Principle:
Principle #35Parameter changes

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 significantly improves the accuracy of identifying painted road markings by eliminating the impact of varying illumination, allowing for more precise analysis and recognition of road features, even under different lighting conditions.

Implementation Method 1

transforming the N bands to log color space values in a log color space

Methodology Applied
Scientific EffectLog color space transformation:

Implementation Method 2

projecting the log color space values to the chromaticity plane to provide chromaticity representation values corresponding to the pixels of the image

Methodology Applied
Scientific EffectChromaticity plane projection:

Data Source

PatentUS10032088B2Method and system for classifying painted road markings in an automotive driver-vehicle-assistance device
Publication Date: 2018.07.24 INNOVATION ASSET COLLECTIVE
  • US10032088B2 patent drawing
  • US10032088B2 patent drawing
  • US10032088B2 patent drawing

AI summary

An automated, computerized method is provided for processing an image. The method includes the steps of arranging a digital camera on a vehicle body, operating the digital camera to provide an image file depicting an image of a scene related to vehicle operation on a road, in a computer memory, receiving from the memory the image file depicting pixels of an image of the scene related to vehicle operation on a road, and using an analysis of the pixels to generate an illumination invariant image of the scene. A further process step includes using the illumination invariant image to analyze the road scene for painted road markings.