Traffic Light Detection via HSV Color Space Segmentation

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Solution Overview

Problem

Autonomous driving vehicles face challenges in accurately identifying the state of traffic lights using machine vision, as existing methods are inefficient and require complex algorithms to analyze images, which can be time-consuming and prone to errors.

Innovation Solution

The solution involves capturing images of traffic lights and cropping them to specific sub-regions based on the vehicle's relative position, then matching these images against a precompiled library of images to determine the state, using similarity scores or dissimilarity analysis to identify the traffic light's state without relying on specialized algorithms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complex algorithms are used to analyze traffic light images, then identification accuracy may improve, but processing time increases and error rate increases

Engineering Contradiction:
Improvetraffic light state identification accuracyVSAvoidimage processing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent segments the traffic light image into multiple color channels (red, green, yellow) and processes each channel separately using simple threshold comparisons. This segmentation approach replaces complex algorithms with straightforward color-space analysis, achieving accurate identification while minimizing processing time.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extracts only the essential color information from the traffic light image by converting to HSV color space and analyzing specific hue ranges. This extraction of key features eliminates unnecessary computational steps, maintaining identification accuracy while significantly reducing processing time compared to full-image complex analysis.

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If complex algorithms are used to analyze traffic light images, then identification accuracy may improve, but system reliability decreases due to higher error rates

Engineering Contradiction:
Improvetraffic light state identification accuracyVSAvoidsystem error rate
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements feedback through confidence score calculation and verification mechanisms. After initial color-based identification, the system calculates confidence levels and can request re-verification if uncertain, reducing error rates while maintaining simple processing. This feedback loop ensures high reliability without requiring complex algorithms.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the analysis parameters from complex pixel-level patterns to simple color space values (HUE, SATURATION, VALUE). By transforming the problem into parameter-based color thresholding, the system achieves both high accuracy and high reliability with minimal processing complexity.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If simple image cropping and matching methods are used, then processing speed improves, but identification accuracy may be insufficient

Engineering Contradiction:
Improveprocessing speedVSAvoidtraffic light state identification accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent transforms the image matching problem into a color parameter comparison task. By converting images to HSV color space and comparing HUE values against predefined thresholds, the system achieves both high processing speed and high identification accuracy, overcoming the limitations of simple pixel-based matching.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces mechanical image cropping and pixel-by-pixel comparison with optical color space transformation and mathematical thresholding. This substitution of the analysis mechanism maintains simplicity and speed while dramatically improving accuracy through robust color-based classification.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11288528B2Differentiation-based traffic light detection
Publication Date: 2022.03.29 BAIDU USA LLC
  • US11288528B2 patent drawing
  • US11288528B2 patent drawing
  • US11288528B2 patent drawing

AI summary

A method, apparatus, and system for determining a state of an upcoming traffic light is disclosed. At an autonomous driving vehicle (ADV), an upcoming traffic light ahead in a direction of travel is detected. A relative position of the ADV to the traffic light is determined based on a three-dimensional (3D) position of the traffic light and a position of the ADV. A first image whose content includes the traffic light is captured. A second image of the traffic light is obtained, which comprises cropping the first image and preserving only a first sub-region of the first image that corresponds to the traffic light. One or more third images of the traffic light are retrieved from a precompiled image library based on the relative position of the ADV to the traffic light. A state of the traffic light is determined based on the one or more third images.