Optical Character Recognition of Amharic Documents - CVIT - IIIT ...

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computers [3]. Nowadays, it is common tofind PC-based OCR systems that arecommercially available. However, most ofthese systems are developed to work withLatin-based scripts [4].Optical character recognition convertsscanned images of printed, typewritten orhandwritten documents into computerreadable format (such as ASCII, Unicode,etc.) so as to ease on-line data processing.The potential of OCR for data entryapplication is obvious: it offers a faster,more automated, and presumably lessexpensive alternative to the manual dataentry devices, thereby improving theaccuracy and speed in transcribing datainto the computer system. Consequently, itincreases efficiency and effectiveness (byreducing cost, time and labor) in informationstorage and retrieval.Major applications of OCR include: (i)Library and office automation, (ii) Form andbank check processing, (iii) Documentreader systems for the visually impaired, (iv)Postal automation, and (v) Database andcorpus development for language modeling,text-mining and information retrieval [2], [5].While the use and application of OCRsystems is well developed for mostlanguages in the world that use both Latinand non-Latin scripts [6], an extensiveliterature survey reveals that fewconference papers are available on theindigenous scripts of African languages.Lately some research reports have beenpublished on Amharic OCR. Amhariccharacter recognition is discussed in [7]with more emphasis to designing suitablefeature extraction scheme for scriptrepresentation. Recognition using directionfield tensor as a tool for Amharic charactersegmentation is also reported [8]. Workuand Fuchs [9] present handwritten Amharicbank check recognition. On the contrary,there are no similar works being found forother indigenous African scripts.Therefore, there is a need to exert mucheffort to come up with better and workableOCR technologies for African scripts inorder to satisfy the need for digitizedinformation processing in local languages.II. AMHARIC SCRIPTSIn Africa more than 2,500 languages,including regional dialects are spoken.Some are indigenous languages, whileothers are installed by conquerors of thepast. English, French, Portuguese, Spanishand Arabic are official languages of many ofthe African countries. As a result, mostAfrican languages with a writing system usea modification of the Latin and Arabicscripts. There are also many languageswith their own indigenous scripts andwriting systems. Some of these scriptsinclude Amharic script (Ethiopia), Vai script(West Africa), Hieroglyphic script (Egypt),Bassa script (Liberia), Mende script (SierraLeone), Nsibidi/Nsibiri script (Nigeria andCameroon) and Meroitic script (Sudan) [10].Amharic, which belongs to the Semiticlanguage, became a dominant language inEthiopia back in history. It is the official andworking language of Ethiopia and the mostcommonly learnt language next to Englishthroughout the country. Accordingly, thereis a bulk of information available in printedform that needs to be converted intoelectronic form for easy searching andretrieval as per users’ need. Suffice is tomention the huge amount of documentspiled high in information centers, libraries,museums and government and private
offices in the form of correspondence letters,magazines, newspapers, pamphlets, books,etc. Converting these documents intoelectronic format is a must in order to (i)preserve historical documents, (ii) savestorage space, and (iii) enhance retrieval ofrelevant information via the Internet. Thisenables to harness existing informationtechnologies to local information needs anddevelopments.Fig. 1: Amharic alphabets (FIDEL) with their seven ordersrow-wise. The 2nd column shows list of basic charactersand others are vowels each of which derived from thebasic symbol.Those African languages using amodified version of Latin and Arabic scriptscan easily be integrated to the existing Latinand Arabic OCR technologies. It is worth tomention here some of the related worksreported at home and in the Diaspora topreserve African languages digitally(predominantly in languages that use Latinscripts). Corpora projects in Swahili (EastAfrica), open source software for languageslike Zulu, Sepedi and Afrikaans (SouthAfrican), indigenous web browser inLuganda (Uganda), improvisation ofkeyboard characters for some Africanlanguages, the presence of Africanlanguages on the Internet, etc. [11].Therefore, we need to give moreemphasis to those indigenous Africanscripts. This is the motivation behind thepresent report. To the best of ourknowledge, this is the first work that reportsa robust Amharic character recognizer forconversion of printed document images ofvarying fonts, sizes, styles and quality.Amharic is written in the unique andancient Ethiopic script (inherited from Geez,a Semitic language), now effectively asyllabary requiring over 300 glyph shapesfor representation. As shown in Fig. 1,Amharic script has 33 core characters eachof which occurs in seven orders: one basicform and six non-basic forms consisting ofa consonant and following vowel. Vowelsare derived from basic characters withsome modification (like by attaching strokesat the middle or end of the base character,by elongating one of the leg of the basecharacter, etc.). Other symbols are alsoavailable that represent labialization,numerals, and punctuation marks. Thesebring the total number of characters in thescript to 310 as shown in Table 1.
Page 1: Optical Character Recognition of Am
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Page 11: VI. RESULTS AND DISCUSSIONSWe have

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