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An Illumination Invariant Traffic Sign Recognition in the Driving Environment for Intelligence Vehicles

지능형 자동차를 위한 조명 변화에 강인한 도로표지판 검출 및 인식

  • 이태우 (연세대학교 컴퓨터과학과) ;
  • 임광용 (LG전자기술원 미래IT융합 연구소) ;
  • 배건태 (연세대학교 컴퓨터과학과) ;
  • 변혜란 (연세대학교 컴퓨터과학과) ;
  • 최영우 (숙명여자대학교 컴퓨터과학과)
  • Received : 2014.07.10
  • Accepted : 2014.11.24
  • Published : 2015.02.15

Abstract

This paper proposes a traffic sign recognition method in real road environments. The video stream in driving environments has two different characteristics compared to a general object video stream. First, the number of traffic sign types is limited and their shapes are mostly simple. Second, the camera cannot take clear pictures in the road scenes since there are many illumination changes and weather conditions are continuously changing. In this paper, we improve a modified census transform(MCT) to extract features effectively from the road scenes that have many illumination changes. The extracted features are collected by histograms and are transformed by the dense descriptors into very high dimensional vectors. Then, the high dimensional descriptors are encoded into a low dimensional feature vector by Fisher-vector coding and Gaussian Mixture Model. The proposed method shows illumination invariant detection and recognition, and the performance is sufficient to detect and recognize traffic signs in real-time with high accuracy.

본 논문은 도로주행 영상에서 도로표지판을 인식하는 방법을 제안한다. 지능형 차량에서 얻어지는 도로표지판 영상은 일반적인 사물 영상과는 다른 두 가지 특징이 있다. 첫째는 대상이 되는 사물들은 종류가 제한적이고 형태가 단순한 도형인 경우가 대부분이다. 둘째는 일반적인 도로주행 영상은 다양한 조명 환경과 날씨 상태로 인해서 선명한 영상을 취득하기 어려운 점이다. 본 논문에서는 조명 변화가 심한 도로주행 영상에 대해서 효과적으로 특징을 추출하기 위해서 Modified Census Transform(MCT)을 개선한 특징추출 방법을 제안한다. 추출된 특징들은 히스토그램으로 쌓여지고 영상 전반에 걸쳐 아주 고차원의 기술자(Descriptor)로 변환되며, 변환된 수많은 기술자들은 가우시안 혼합 모델(Gaussian Mixture Model)을 활용한 Fisher-vector 방법에 의해서 저차원으로 변형하여 특징으로 사용한다. 본 논문에서 제안하는 방법은 일반적인 표지판 인식 방법에 비해서 조명변화에 강한 검출 결과를 보여주었으며, 실시간 검출 및 인식도 가능하였다.

Keywords

Acknowledgement

Supported by : 한국연구재단

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