Size and rotation invariant alphabet recognition

Junho Rim, Chulhee Lee

Research output: Chapter in Book/Report/Conference proceedingConference contribution


As more vehicles and devices are becoming equipped with cameras, computer vision technologies can significantly enhance functionalities. Among various computer vision applications, alphabet recognition has been an important application. Alphabet recognition is a basic operation in text recognition of natural images, which can be used to obtain useful information from visual information. It can be used for vehicles or autonomous moving machines such as drones or robots to understand surrounding environments. A main difficulty is that alphabets can take various sizes and orientations. Thus, it is desirable to develop recognition algorithms that are size and rotation invariant. In this paper, we propose alphabet recognition algorithms based on the recently proposed angle-distance map, which is robust against size and rotation variations. Using the two features (distance and angle), the angle-distance map is generated, and a rotation invariant matching algorithm is developed. Since the distance is normalized, the map is size-invariant. Experimental results showed promising results.

Original languageEnglish
Title of host publicationUnmanned Systems Technology XIX
EditorsHoa G. Nguyen, Robert E. Karlsen, Charles M. Shoemaker, Douglas W. Gage
ISBN (Electronic)9781510608917
Publication statusPublished - 2017
EventUnmanned Systems Technology XIX Conference 2017 - Anaheim, United States
Duration: 2017 Apr 112017 Apr 13

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherUnmanned Systems Technology XIX Conference 2017
Country/TerritoryUnited States

Bibliographical note

Publisher Copyright:
© 2017 SPIE.

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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