Bangla Handwritten Pin Code String Recognition for Indian Postal Automation

Indian pin code is a six-digit string. Because of the writing style of different individuals some of the digits in a pin code string may touch with its neighboring digits. Accurate segmentation of such touching components into individual digits is a difficult task. To avoid such segmentation, here we consider a pin code string as word and the pin code recognition problem is treated as lexicon free word recognition. In the proposed method, at first, binarization of the input document is done. Next, water reservoir concept is applied to pre-segment a pin code string into possible primitive components (individual digits or its parts). Presegmented components of the pin code are then merged into possible digits to get the best pin code. In order to merge these primitive components into digits and to find optimum segmentation, dynamic programming (DP) is applied using total likelihood of digits as the objective function. To compute the likelihood of a digit, modified quadratic discriminant function (MQDF) is used. The features used in the MQDF are based on the directional information of the components. Our system on handwritten Bangla pin code shows 99.08% reliability when rejection and error rates are 19.28% and 0.74%, respectively.