Semi-Automatic Generation of Arabic Digital Talking Books

Transcription

1 Semi-Automatic Generation of Arabic Digital Talking Books Iyad Abu Doush 1, Faisal Alkhateeb 2 and Abed Al Raoof Bsoul 3 Computer Science Department Yarmouk University Irbid - Jordan { 1 iyad.doush, 2 alkhateeb, 3 raoofbsoul}@yu.edu.jo Abstract A very small percentage of books are available in accessible format for people with print disabilities (e.g., people with visual impairment and people with learning disabilities). The authors and publishers of e-books usually do not include certain features to make the e-book accessible. Digital talking books are electronic documents encoded in DAISY format. The purpose of this format is to provide access-for-all to digital information. This paper presents a framework for semiautomatic building of DAISY digital talking books for the Arabic language. The presented framework include: image-to-text converter, context-injector, text-to-audio-generator, and DAISY generator. Keywords - DAISY; digital talking books; optical character recognition (OCR); assistive technologies; print disabilities I. INTRODUCTION Reading printed contents (e.g., books and newspapers) is not an easy task for people who have difficulty in accessing visual material (e.g., people with visual impairment, a driver going to work, or people with learning disabilities such as dyslexia). Reading books are crucial in the preparation of students to enter careers. Most of the printed books have an electronic alternative. However, a large amount of Arabic electronic books are available they are not in a format accessible for assistive technologies (i.e., Adobe s Portable Document Format (PDF)). This format cannot be presented by assistive devices (e.g., Braille displays and speech synthesizers). For example, when the a blind user opens a PDF file that contains Arabic text the screen reader will not be able to read the text to the user. An increasing number of people with print disabilities in the Arab world are using the Web to take advantage of educational opportunities that were previously inaccessible. In 2011 a report by the World Health Organization (WHO) illustrates that every 5 seconds one person in the world becomes blind. The number of visually impaired persons in the Arab world is more than 37 million, out of this number 5.3 million are blind persons. In spite of these numbers, people with visual impairment in post-secondary institutions are low. This segment of population is also highly under-represented in the workplace. The United Nations Convention on the Rights of Disabled Persons (2006) established a commitment from the governments to give people with disabilities equal rights to access different facilities provided to the society. For a person who has visual impairment or a reading disability it is not possible to read printed documents [1]. The solution sometimes is to present these documents in Braille encoding which is expensive to produce, and not all persons with visual impairment can read Braille. Others may request the help of someone who can read for them the contents either printed or from the computer screen. The person who will read for them may not always be available or maybe frustrated to read for a long time. It is important to offer equal access to information for all users regardless of their disability. This multimodal access to information would help people with disabilities to be more independent. Such solution may benefit also people without disabilities who would like to hear and see text for better understanding or they may would like to hear only the book in audio format (e.g., while driving the car). Publishing accessible digital information at no greater cost is a key issue for people with print disabilities (e.g. elderly people with visual impairment and people with reading disabilities). DAISY (Digital Accessible Information System) [2] is an open standard format for digital talking books which enable the users to listen and pass through text materials which are rendered in audio. Usually manual conversion for the e-documents is used to convert the materials into easy to access and easy to use form for students with visual impairments. This process is time consuming due to the numerous steps must to be followed manually [3]. This paper presents a framework for a complete system for semi-automatic building of DAISY books for the Arabic language. The development of this framework will provide accessible format for books that can be used by students, teachers, and general readers with different backgrounds and disabilities. This can help in reaching users with diverse backgrounds, interests, abilities and disabilities. Several Arabic books are available in PDF format or as images and this format cannot be directly converted into DAISY format. The books have to be in text format in order to be converted easily into DAISY format. Automatic generation of DAISY books is still not explored for the Arabic language /14/$ IEEE 237

2 The generated Arabic digital talking book can be easily translated into different formats: Braille, large print, synthetic speech, printed book, PDF, or HTML. Books on DAISY format can run on particular hardware, several applications and other portable devices (e.g. smart phones). II. BACKGROUND People with print disabilities cannot use printed materials to access information. Electronic documents are an alternative that can be used with assistive technologies to access the document contents. Contini et al. [1] presented the main characteristics that make an electronic document accessible : The document format has to be accessible (e.g. TXT or X/HTML) by assistive technologies (e.g., screen reader or magnifier). The figures or graphs in the document should have alternative textual descriptions. The tables or diagrams have to be organized in a way that will make them readable when linearized by the screen reader. Different methods are used by visually impaired students and individuals to access books with Arabic content. The alternatives are: the book printed in Braille, audio books, accessing books using speech synthesizer, and reading the book by a sighted person. The limitations of the existing approaches to access printed contents by people with visual impairment can be summarized as follows: Reading books requires the continuous interplay between reading, skipping, and re-reading. Some of the existing approaches do not allow exploring of the book by the student (e.g., audio book). Other approaches require the student to have the skill of reading Braille, and it is expensive to produce such books. Also, the user navigation is linear [4]. While reading the book it is important to bookmark where you stopped, to continue the reading from there next time. Another issue is the ability to copy important parts of the book by the visually impaired students or individuals. A tagged PDF [5] is a PDF document that its structure (i.e., text, graphics, and images) is presented using tags. Such semantic information can help in more accurate text extraction and in PDF accessibility. In [6] the authors studied the limitations of converting non-tagged PDF into DAISY format and found that in order to reach the correct tagging of the document human intervention is required. Arabic OCR: An extensive literature exists on solving the problem of recognizing machine-printed Arabic texts. Solving this problem is usually divided into two phases: Segmentation phase, in which the system extract specific features in order to isolate the letter. Recognition phase, the input is the letter image extracted in the segmentation phase, and then a feature similarity will be used to recognize the character. Bushofa and Spann [7] proposed an algorithm that split into characters the Arabic words using the angle of the character according to a base line. Another work by Zheng et al. [8] use the explicit segmentation. The algorithm divided the segmenting process into three levels: dividing the text into lines, each line is splitted into words, and split into characters each word. Al-Taani and Al-Haj [9] developed an algorithm that recognizes on-line Arabic handwritten characters. Several features are used in the recognition phase (number of segments, left-right density ratio, bottom-up density ratio and others). A classification structure (i.e., decision trees) is then used to identify the class of each character. Arabic Speech Synthesizer: Speech synthesis is the process of automatically generating speech from text [10]. One type of such systems is based upon merging continuously small speech elements which are saved into speech database [11], [12]. For example, Rashad et al. [12] develop a diphone speech synthesis system for the Arabic language using MARY TTS [13], where a diphone is a unit that begins in one phone middle and continues to the next one middle. The system has been evaluated using the Diagnostic Rhyme Test (DRT) that measures how the synthesized speech is intelligent and the Categorical Estimation Test (CE) that measures how is the excellence of the synthesized speech is in general. A similar system that uses MBROLA synthesizer [14] based on diphone concatenation has been proposed in [15]. The system generates speech synthesis by classifying the voice source into different types and then estimating the format. Allophones means the different pronunciations for the letter sound in the language. In another work Elshafei [16] propose an Arabic text-to-speech system based on a set of Arabic allophones. The proposed system contains also a set of Arabic letter-to-sound rules. Khalifa et al. [17] develop a hybrid Arabic speech synthesizer which use phonemes as speech element. The system is based on Sinusoidal model and concatenation. To be vocabulary independent, the system contains a set of rules to achieve letter-to-sound mapping and an exception lexicon to speak words that do not go after a pronunciation rule. An Arabic SSML [18] (Speech Synthesis Markup Language) system has been proposed in [19]. This markup language is used to enable control the speech output (pronunciation, volume, pitch, rate, etc.) on voice browsers. III. METHODOLOGY The overall goal of the proposed framework is to develop an integrated framework for delivering electronic Arabic books in accessible format (i.e., DAISY). The framework will help people with print disabilities in exploring and reading Arabic books. The design of the framework will be as follows: 238

3 Input format: the widely used format for electronic in the font size and style can be used to indicate the books is PDF. Usually it is converted from text or section header of the book. This needs a user intervention from images. The PDF book will be converted into to confirm the tag structure of the PDF document (e.g., text format. used detect structural information such as changes in visual formatting of the document. For example, changes Convert text into audio: Arabic speech synthesizer page layout structure and structural information). The will be used to convert the generated text into audio. images and graphics in the page would need a user Generate a digital talking book: the generated text intervention to explain them using alternative text. book and the generated audio book will be connected 3. Context-injector: The extracted text will be processed together using structured XML and HTML files to with context information, book Metadata and hierarchical generate the DAISY book. and organizational information (e.g., subsections and The DAISY format gives the user the ability of tables). The result will be the A digital talking book XML converting the digital book into different formats according to file. his/her preference. The steps to convert printed book into 4. Text-to-audio-generator: Generate the equivalent audio DAISY book is shown in Fig. 1. books for the generated text book using speech In order to develop the automatic Arabic DAISY books synthesizer. We can use available Arabic speech generator we need to: synthesizer (e.g., Acapellaa [23]) as part of the framework to convert the Arabic text into speech (audio). 1. Collect a corpus of 10 digital Arabic books in PDF formats from online resources (e.g., [21]). 5. DAISY generator : A digital talking book is a set of XML files for textual contents, control navigation and 2. Image-to-text converter: Convert the Arabic PDF books text to audio synchronization, in addition to the audio files into text format. We will use optical character recognition in MP3 (see Fig. 2). A sample of the main XML file is (OCR) to convert images in PDF into Arabic text. We can shown in Fig. 3. These files will be connected together in use available Arabic OCR (e.g., ABBYY FineReader order to generate the DAISY book (i.e., generating the [22]) as part of the framework to convert the Arabic PDF digital talking book). book into text. Some PDF files include semantic structure 6. An evaluation test will be performed to verify that the in the document (i.e., tagged PDF). This type can be output is what is expected according to the objective of converted into DAISY format easier as the structure the framework. markup is embedded in the document. Other PDF files suffer from the absence of such markups that make it 7. The consolidation of different parts of the project into one harder to convert them. A more complex approach can be framework. The preliminary implementation of the proposed framework is shown in Fig.4. Fig. 2. Files needed to generate the DAISY book <dtbook> <head> (Information About the Book) </head> <book> (The entire content of the book, including cover information, etc.) </book> </dtbook> Fig. 1. Steps needed to generate accessible e-document [20] Fig. 3. Sample of DAISY encoding tags [24] 239

4 The developed framework would help in accomplishing the following goals: Increase the number of available digital talking books as DAISY is the main digital book format to be used by people who are blind or visually impaired and other people with print disabilities. Synchronized audio and text highlighting benefit people with dyslexia, people with learning disabilities, and those who learn a foreign language. The digital talking books can be published online to benefit larger group of users in the Arab world. Converting books of schools and universities in the Arab world into digital DAISY format to make it easier for students with different kinds of disabilities to study independently. The digital talking book can be used by other people who have difficulty in accessing the visual material. For example a person driving to work for a long period of time can listen using MP3 or mobile phone to a digital talking book. IV. CONCLUSION Preparing accessible e-documents for people with print disabilities is not an easy task In this paper we presented a framework for building a widely adopted accessible format for digital books (i.e. DAISY) for the Arabic language. The generated digital talking book can be used with those who have difficulty in accessing the visual material whether it is because of visual impairment circumstances (e.g. learner driving to work) or person with learning disability such as dyslexia. Using the proposed framework an automatic transformation of the e-document into an accessible format (i.e., DAISY). Currently, we are developing the implementation of the proposed design. Later on, we will work on evaluating the accuracy of the generated books in terms of generation time, words recognition and speech quality. ACKNOWLEDGMENT This research project is funded by the Jordanian Scientific Research Support Fund. Fig. 4. A snapshort of the proposed system 240

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