Real-Time Traffic Sign Recognition Using Binary Masks and Temporal Smoothing

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Solution Overview

Problem

Current traffic sign recognition systems face challenges such as within-class variability, between-class similarity, background clutter, motion blur, adverse weather conditions, and variations in sign design across countries, which hinder accurate identification of traffic signs in images.

Innovation Solution

A real-time Traffic Sign Recognition system comprising a preprocessing stage for identifying image regions, a localization stage for accurate sign detection, a classification stage using feature extraction and machine learning classifiers, and a temporal smoothing stage to filter noise and false detections, employing techniques like morphological operations, extended radial symmetry transform, and temporal smoothening with the Jaccard coefficient.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If color information extraction and morphological operations are applied to identify traffic signs, then detection accuracy is improved, but processing time increases

Engineering Contradiction:
Improvetraffic sign detection accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The image processing is divided into multiple stages: preprocessing with color extraction, morphological operations for refinement, and final classification. This segmentation allows each stage to focus on specific tasks, improving overall accuracy while enabling parallel processing optimizations to mitigate time loss.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Color information extraction and binary mask creation are performed as preliminary actions before main classification. The morphological opening operation is applied early to refine masks and remove noise, preparing the data for more efficient subsequent processing and reducing the computational burden on later stages.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If multiple color masks and morphological operations are applied, then false detections are reduced, but system complexity increases

Engineering Contradiction:
Improvedetection reliabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The detection system is segmented into distinct processing stages: color extraction, binary mask generation, morphological operations, and classification. Each stage handles a specific aspect of the problem, making the complex system more manageable and maintainable while improving reliability through staged verification.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Binary masks serve as intermediary representations between the raw color information and the final classification decision. The morphological operations on these masks act as an intermediary filtering step that reduces false detections before the data reaches the classification stage, thereby improving reliability without directly complicating the core classification algorithm.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If temporal smoothening is applied to remove noise, then false positives are reduced, but processing delay increases

Engineering Contradiction:
Improvefalse positive reductionVSAvoidprocessing delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

Temporal smoothening is applied as a preliminary action to detected traffic signs before final classification and output. By filtering temporal noise early in the processing pipeline, the system reduces false positives that would otherwise require more complex verification, thereby improving reliability while limiting the delay to a single smoothening pass.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The temporal smoothening operates continuously on the stream of detected signs, maintaining a rolling window of recent detections to filter false positives. This continuous operation allows the system to maintain reliability improvements without introducing batch-processing delays, as the smoothening is integrated into the real-time detection flow.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentUS11398098B2Real time traffic sign recognition
Publication Date: 2022.07.26 TEXAS INSTRUMENTS INC
  • US11398098B2 patent drawing
  • US11398098B2 patent drawing
  • US11398098B2 patent drawing

AI summary

Advanced driver assistance systems can be designed to recognize and to classify traffic signs under real time constraints, and under a wide variety of visual conditions. This disclosure provides techniques that employ binary masks extracted by color space segmentation, with a different binary mask generated for each sign shape. Temporal tracking is employed to add robustness to the detection system. The system is generic, and is trainable to the traffic signs used in various countries.