A Proposed Recognition System For Handwritten Devnagri Script And English Numerals Using ANN

A Proposed Recognition System For Handwritten Devnagri Script And English Numerals Using ANN

Mr. T B Wagh Department CSE GHRIEM

Jalgaon, India

Mr. Chandrashekhar Badgujar

Department CSE GHRIEM

Jalgaon, India

Abstract In this paper, a system for recognizing hand written Devnagari script and English Numerals is presented. The system considers a handwritten images as an input, separates the lines, words, numerals and then characters step by step and then recognizes the character using artificial neural network approach, in which Creating a Character Matrix and a corresponding Suitable Network Structure is key. In addition, information of how one is Deriving the Input from a Character Matrix must first be obtained before one may proceed. Afterwards, the Feed Forward Algorithm gives insight into the entire working of a neural network; followed by the Back Propagation Algorithm which compromises Training, Calculation of Error, and Modifying Weights. Once the characters are recognized they can be replaced by the standard fonts. to integrate information from diverse sources.

Key WordsDevnagari, English Numerals character matrix, recognition, neural network, network structure.

1. INTRODUCTION II.

   This paper is based on work done by K. Y. Rajput and Sangeeta Mishra on Devanagari script and G S Lehal and Nivedan Bhatt on English Numerals.[1] Devanagari script is a logical composition of its constituent symbols in two dimensions. It has eleven vowels and thirty three simple consonants. A horizontal line is drawn on top of all characters which is referred to as the header line or shirorekha. A character is usually written such that it is vertically

   separate from its neighbors. Devanagari script has many multi-stroke characters. The data entry

   recognition mechanisms need to deal with such multi-stroke characters and also conjuncts that are made up by joining two or more characters partially. During experiments it was found that the Devnagri numeral set had a much better recognition and rejection rate as compared to the English character set and so the input numeral is first tested by the Devnagri module[2]. One of the most classical applications of the Artificial Neural Network is the Character Recognition System. This system is the base for many different types of applications in various fields, many of which we use in our daily lives. Cost effective and less time consuming, businesses, post offices, banks, security systems, and even the field of robotics employ this system as the base of their operations. Whether you are processing a check, performing an eye/face scan at the airport entrance, or teaching a robot to pick up and object, you are employing the system of Character Recognition. One field that has developed from Character Recognition is Optical Character Recognition (OCR). OCR is used widely today in the post offices, banks, airports, airline offices, and businesses. The Address readers sort incoming and outgoing mail, check readers in banks capture images of checks for processing, airline ticket and passport readers are used for various purposes from accounting for passenger revenues to checking database records. The Form readers are used to read and process up to 5,800 forms per hour. OCR software is also used in scanners and faxes that allow the user to turn graphic images of text into editable documents. Newer applications have even expanded outside the limitations of just characters. Eye, face, and fingerprint scans used in high-security areas employ a newer kind of recognition. More and more assembly lines are becoming equipped with robots scanning the gears that pass underneath for faults, and it has been applied in the field of robotics to allow robots to detect edges, shapes, and colors[3].And country like India were many

   languages are used to write for example Devnagari script and English Numerals it become difficult to indentify multiple language Character . Optical Character Recognition to has even advanced into a newer field – Handwritten Recognition, which of course is also based on the simplicity of Character Recognition. The new idea for computers, such as Microsofts new Tablet PC, is pen-based computing, which employs lazy recognition that runs the character recognition system silently in the background instead of in real time. Before reaching for final recognition of the character, the document is separated into line then into words and then finally into characters [4][5]. In this paper we shall be presenting a technique to recognize a devnagari and English Numerals hand written characters using neural network[6].

2. STEPS

   The entire system can be divided in three parts.

   1. Character Separation.

   2. Preprocessing.

   3. Character recognition and editing.

3. CHARACTER SEPARATION

   Line Segmentation: Generally the problems encountered in the detection process are of two types

   1. all words in a text lines are not aligned, and 2) gap between text lines is not uniform; At some places the gaps between the lines may be zero. Approach used in this system is based on the histogram at an inclination of the binary image. First we find the horizontal density histogram of a few rows in the image.

   Word Segmentation: Word boundaries are detected by looking for the vertical gaps in the segmented line, and checking them to identify the beginning and end of words.

   Character Segmentation: After detection of reference line it is removed from the word to separate out the characters again by looking for vertical gaps in the segmented word, and checking them to identify the beginning and end of character.

4. PREPROCESSING

   Before the separated characters are given to the character recognition system by neural network they need to be brought in a format that is standard and acceptable to the neural network as input. This needs preprocessing. The aim of the paper is to develop an OCR for devanagiri script using ANN to model the characters. The Devanagiri script is used in Sanskrit,

   Hindi , Marathi and Nepali languages and OCR developed can be used for applications to these languages. The text is also assumed to consist of simple characters along with the headline. Various blocks of the preprocessing system are as follows:

   • Image Binarisation

   • Thinning of binarised image and

   • Windowing

     Image Binarisation:

     In image binarisation , the text image which is gray scale image is converted into a binary image with each pixel taking a value of 0 or 1 depending on threshold value of the image. The technique is most commonly employed for determining the threshold involves analyzing the histogram of gray scale levels in the digitized image .

     I(x,y) = 0 I(x,y)<t

     = 1 I(x,y)>=t

     Thinning of Binarised Image:

     The characters of the text page have to be thinned prior to recognition. Thinning removes the points in such a way that only the skeleton of a branch pattern remains. Thinning algorithms transform an object into a set of simple digital arcs. The structure is not influenced by small contour inflections. The basic approach of thinning algorithm is to delete from the object x simple border points, that have more than one neighbor in x and whose deletion does not locally disconnect x.

     X4	X3	X2
     X5	P	X1
     X6	X7	X8

     Figure 1. Thinningof Binarised Image.

     Windowing:

     Windowing the character means to bring the character to a standard image window size. This is required because after segmentation each character may have a different window size thus giving different features for the same character. Windowing is done in two ways. First the character is fitted in a

     tightest possible bounding box so that the background area surroundings and which does not contain any useful information can be removed .Secondly the character size is increased to a standard size in such a way that the connectivity as well as shape of the characters are preserved. This is done, by expanding the characters to standard size, where intermediate pixels can be easily interpolated.

5. CREATING A CHARACTER RECOGNITION SYSTEM

• Character recognition by neural network

• Replacing the recognized characters by standard fonts.

• Assembling all the separated characters in the same order as they appeared in the input image to give final output. The Character Recognition System must first be created through a few simple steps in order to prepare it for presentation into MATLAB. The matrixes of each letter of the alphabet must be created along with the network structure. In addition, one must understand how to pull the Binary Input Code from the matrix, and how to interpret the Binary Output Code, which the computer ultimately produces the Character Matrixes. A character matrix is an array of black and white pixels; the vector of 1 represented by black, and 0 by white. They are created manually by the user, in whatever size or font imaginable; in addition, multiple fonts of the same alphabet may even be used under separate training sessions. Creating a Character Matrix First, in order to enable a computer with the ability to recognize characters, we must first create those characters. The first thing to think about when creating a matrix is its size that will be used. Too small and all the letters may not be created, especially if you want to use two different fonts. On the other hand, if the size of the matrix is very large, it may lead to few problems: Despite the fact that the speed of computers double every third year, their may not be enough processing power currently available to run in real time. Training may take days, and results may take hours. In addition, the computers memory may not be able to handle enough neurons in the hidden layer needed to efficient and accurately process the information. However, the number of neurons may just simply be reduced, but this in turn may greatly increase the chance of error[7]. Before the characters are recognized they must made available in a proper form, this is done by line separation, word separation and then character separation. The steps involved in recognition of character are: Matrix generation, Thinning of Binarised Image, Windowing, Feature Extraction, Training phase and database of trained neural networks for each character.

Matrix generation:

A large matrix size of 30 x 30 is created, through the steps as explained above, because it may not be able to process in real time

Figure 2. Matrix size of 30 x 30 for a English numerals and devnagari character

Neural Network:

The network receives the 900 Boolean values as a 900- element input vector. It is then required to identify the letter by responding with a 49-element output vector. The 49 elements of the output vector each of them represent a letter. To operate correctly, the network should respond with a 1 in the position of the letter being presented to the network. All other values in the output vector should be 0. In addition, the network should be able to handle the noise. In practice, the network does not receive a perfect Boolean vector as input. Specifically, the network should make least possible mistakes while classifying vectors with noise of mean 0 and standard deviation of 0.2 or less.

Architecture:

The neural network needs 900 inputs and 49 neurons in its output layer to identify the character. The network is a two layer log-sigmoid/log-sigmoid network. The log-sigmoid transfer function was picked because its output range (0 to 1) is perfect for learning to output Boolean values. The hidden (first) layer has 600 neurons. This number was picked by guesswork and experience. If the network has trouble in learning, then neurons can be added to this layer. The network is trained to output 1 in the correct position of the output vector and to fill the rest of the output vector with 0's. However, noisy input vectors may not result in the network.

i) Training phase and database of trained ANNs for each character:

The neural network classification techniques such as multilayer perceptrons trained by Error Back Propagation (EBP) algorithm.

The result is expected that it will identify the both character devnagri and English numerals at time for example figure .

Fig 2 Handwritten image as Input image

Fig 3 Expected output

CONCLUSION

The method for recognition of devnagari script and English Numerals using neural network presented in this paper we shown the proposed work for recognize most of multiple the hand writings. However, the success of the method lies in the size of database, i.e. larger the size of database used for training the neural network higher is probability of successful recognition. However the larger data base places the limit on the speed of recognition, and hence this method can be used for offline recognition.

REFERENCES

1. K. Y. Rajput and Sangeeta Mishra Recognition and Editing of DevnagariHandwriting Using Neural Network Proceedings of SPIT-IEEE Colloquium and International Conference, Mumbai, India

2. G S Lehal and Nivedan Bhatt A Recognition System for Devnagri and English Handwritten Numerals

3. Krishnamachari Jayanthi ,Akihiro Suzuki,Hiroshi Kanai,Yoshiyuki Kawazoe, Masayuki Kimura and Keniti Kido, Devnagari character recognition using structure analysis, IEEE-1989.CH2766-4/89/0000- 0363.

4. Dileep Kumar , An AI approach to hand written Devnagari script recognition, IIT Delhi.

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