Addis Ababa University School of Graduate Studies School of Information Science
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ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES SCHOOL OF INFORMATION SCIENCE FEATURE EXTRACTION AND CLASSIFICATION SCHEMES FOR ENHANCING AMHARIC BRAILLE RECOGNITION SYSTEM SHUMET TADESSE JUNE 2011 ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES SCHOOL OF INFORMATION SCIENCE FEATURE EXTRACTION AND CLASSIFICATION SCHEMES FOR ENHANCING AMHARIC BRAILLE RECOGNITION SYSTEM A Thesis Submitted to the School of Graduate Studies of Addis Ababa University in Partial Fulfillment of the Requirements for the Degree of Master of Science in Information Science By SHUMET TADESSE JUNE 2011 ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES SCHOOL OF INFORMATION SCIENCE FEATURE EXTRACTION AND CLASSIFICATION SCHEMES FOR ENHANCING AMHARIC BRAILLE RECOGNITION SYSTEM By SHUMET TADESSE Name and signature of Members of the Examining Board Name Title Signature Date Ato. Henock_________________Chairperson ____________ ________________ Dr. Million Meshesha__________ Advisor, ____________ ________________ Dr. Dereje Teferi______________ Examiner, ____________ ________________ Dedicated to my mother i ACKNOWLEDGEMENT First and foremost, I am ever grateful to the omnipresent God who made things possible to accomplish the two-year program at AAU. I am also heartily thankful to my advisor, Dr. Million Meshesha, whose encouragement, guidance and support from the initial to the final level enabled me to develop an understanding of the subject. His sage advice, insightful criticisms, and patient encouragement aided the writing of this thesis in innumerable ways. Besides his expertise, I really appreciate his patience and thank him for his concern and perspective advice through my thesis work as well as course of Master’s program. My greatest gratitude also goes to Mekelle University (MU) for granting me study leave with the necessary benefits, without which I could not have been able to join my M.Sc. study here in AAU. I also extend my sincere thanks to academic and administrative staffs of Department of Computer Science (MU). My utmost gratitude is extended to my friends especially to Adane L., Belete B., Dereje Y., Esubalew K., Fentaw F., Kindie A., Minillik H., Tariku A., Tadele A. and Zewedie M. whose friendship, hospitality, knowledge, and valuable assistance have supported me in one way or another in the preparation and completion of this study. I would like to thank AAU and all School of Information Science community (instructors, students and administrative staffs) who have a significant contribution in one way or another during my research work. Last but not least, my sincere thanks also forwarded to my family. I am thankful to my mother, whom I dedicate my work, her love and best wishes, despite of her physical absence with me, have helped me in the successful completion of my study at AAU. It is a pleasure to express my gratitude wholeheartedly to my sisters and brothers, Aynalem, Birtukan, Fasil and Mekonnen for their inseparable support and care. Shumet Tadesse ii TABLE OF CONTENTS ACKNOWLEDGEMENT ...............................................................................................ii LIST OF FIGURES ....................................................................................................... vii LIST OF TABLES .......................................................................................................viii ABSTRACT ................................................................................................................... xi CHAPTER ONE ............................................................................................................ 1 INTRODUCTION ..................................................................................................... 1 1.1. Background ................................................................................................... 1 1.1.1. Braille Writing System ........................................................................... 2 1.1.2. Braille Recognition ................................................................................. 3 1.2. Statement of the Problem and Justification ..................................................... 6 1.3. Objectives of the Study .................................................................................. 8 1.3.1. General Objective ................................................................................... 8 1.3.2. Specific Objectives ................................................................................. 9 1.4. Methodology ................................................................................................. 9 1.4.1. Literature Review ................................................................................... 9 1.4.2. Data Collection ..................................................................................... 10 1.4.3. Design and Development of Amharic Braille Character Representation 10 1.4.4. Implementation Tools ........................................................................... 10 1.4.5. Testing Procedure ................................................................................. 11 1.5. Scope and Limitation of the Study ............................................................... 12 1.6. Significance of the Study ............................................................................. 12 1.7. Organization of the Study ............................................................................ 13 CHAPTER TWO......................................................................................................... 14 LITERATURE REVIEW ....................................................................................... 14 2.1. Overview ..................................................................................................... 14 2.2. Amharic Writing System ............................................................................. 14 2.2.1. Amharic Characters .............................................................................. 15 2.2.2. Amharic Numerals and Punctuation Marks ........................................... 16 2.3. Amharic Braille ........................................................................................... 16 iii 2.3.1. Amharic Braille Evolution .................................................................... 16 2.3.2. Amharic Braille Code Characters .......................................................... 18 2.3.2.1. Amharic Braille Character for Core Letters ..................................... 19 2.3.2.2. Amharic Braille Character for Numerals ......................................... 21 2.3.2.3. Amharic Braille Character for Punctuation Marks ........................... 21 2.3.3. Braille Writing and Reading System ..................................................... 22 2.3.3.1. Braille Writing ................................................................................ 22 2.3.3.2. Braille Reading ............................................................................... 23 2.3.3.3. Nature of Amharic Braille Embossed .............................................. 24 2.4. Features and Challenges of Braille Documents ............................................ 24 2.5. Optical Braille Recognition System Overview ............................................. 27 2.5.1. Image Acquisition/Digitization ............................................................. 27 2.5.2. Image Pre-processing............................................................................ 28 2.5.3. Segmentation ........................................................................................ 29 2.5.4. Feature Extraction ................................................................................ 30 2.5.5. Classification ........................................................................................ 32 2.6. Review of Related Works ............................................................................ 33 2.6.1. Optical Braille Recognition System for English Characters ................... 33 2.6.2. Optical Braille recognition System for Spanish Characters.................... 38 2.6.3. Optical Recognition of Braille Writing Using Standard Equipment ....... 39 2.6.4. Image Processing Techniques for Braille Writing Recognition.............. 41 2.6.5. Optical Braille Recognition System for Arabic Characters .................... 42 2.6.6. Optical Braille Recognition System for Amharic Characters ................. 43 CHAPTER THREE .................................................................................................... 46 BRAILLE RECOGNITION TECHNIQUES ......................................................... 46 3.1. Design of Amharic OBR system .................................................................. 46 3.2. Image Acquisition/Digitization .................................................................... 46 3.3. Feature Extraction........................................................................................ 48 3.3.1. Fixed Cell Measures ............................................................................. 49 3.3.2. Horizontal and Vertical Projection ........................................................ 50 3.3.3. Grid Construction ................................................................................. 51 iv 3.4. Classification ............................................................................................... 53 3.4.1. General Approaches for Solving a Classification Problem .................... 54 3.4.2. Decision