Recognition of Assamese Handwritten Numerals Using Mathematical Morphology

Authors Kalyanbrat Medhi Dr. Sanjib Kr. Kalita

Dept. of Computer Science, Gauhati University

Presented by Kalyanbrat Medhi

Introduction

• The problem of Assamese handwritten digits recognition is considered.

• Mathematical morphology is used.

• The ISI Kolkata data sets are used for testing.

• Applications – postal code reading

– license plate reading

– price recognition etc.

• Recognition Technique – On-Line Recognition

– Off-Line Recognition

• we use the off-line technique for digit recognition

Methodology(1)

• blobs and stems are used to recognize

• Blobs can identified with the help of boundary trace method considering the property as hole.

• The method takes binary image as input and returns the exterior boundaries of the image.

• Subtract those boundaries that are not related to blobs of the image

• It is seen that there are two boundaries are not that covering the blobs.

Methodology(2)

• Stems are identified as

– By using matlab function edge() get an intermediate image.

– Calculate number of pixels in each column and row of the intermediate image.

– If more than 1/3 rd rows contain two non-zero pixels then vertical stems exist.

– If more than 1/3 rd columns contain two non-zero pixels then horizontal stems exist

• Unnecessary small stems are not detected.

Methodology(3) Care should be taken

– Image need to crop properly

– Image should be not too small.

• An input image is resized to size 44x35.

• Then image is converted to binary image.

• Morphological-dilation followed by erosion on that binary image.

• Small objects are removed using morphologically opening the image

• image placed at the root node of decision tree.

• Next action is performed depending of feature of the node.

• The algorithm is as follows

Methodology(4)

• Step1.Count the number of blobs in the image. • Step2.If number of blobs in step 1 is 1 go through step 3 to step 7 and if

0 go through step 8 to step 15 • Step3.Find the number of vertical stems and horizontal stems with

position up and down. • Step4.If number of vertical and horizontal stems in step 3 is 2 then digit is

৮ (8). If number of stems in step 3 is 1 and position of stems is up it is ১ (1). If number of stems in step 3 is 1 and position of stems is down it is ৭ (7).

• Step5.If number of vertical and horizontal stems in step 3 is 0 then check the number of blobs found in step 1. If number of blobs in step 1 is 2 digit is ৪ (4). If number of blobs in step 1 is 1 go through step 6 to step 7.

• Step6.Draw line vertically right of the digit and count the number of blobs in that image.

• Step7. If number of blobs in step 6 is 2 digit is ৫ (5). If number of blobs in step 6 is 2 digit is ০ (0).

Methodology(5)

• Step8.Draw line middle of the digit horizontally. Count the number of blobs in that image.

• Step9.If number of blobs in step 8 is 1 then go through step 10 to 13 and if 0 go through step 14 to 15.

• Step10.Draw line middle of the digit vertically. Count the number of blobs in that image.

• Step11.If number of blobs in step 10 is 3 digit is ৩ (3). If number of blobs in step 10 is 2 go through step 12 to 13.

• Step12.Draw line left of the digit vertically. Count the number of blobs in that image.

• Step13. If number of blobs in step 12 is 3 digit is ৯ (9). If number of blobs in step 12 is 2 digit is ৬ (6).

• Step14.Draw line right of the digit vertically. Count the number of blobs in that image.

• Step15.If number of blobs in step 14 is 1 digit is ২. If number of blobs in step 14 is 0 digit is ১ (1).

Methodology(6)

Methodology(7)

Methodology(8)

Methodology(9) • Assamese digit {১} without blobs and with blobs as depicted

in figure (to right hand)

• If the stems is above the blobs then it is {১} and stems is below the blobs then it is {৭}.

• Similarly digit {৮} may be with blobs or without blobs as bellow

• But when we draw line horizontally through middle of digit we obtain one blobs in {৮} and zero blobs in {২}.

Result of Experiment(1)

Recognition success rate of various handwritten Assamese numerals

Result of Experiment(2)

Recognition process in matlab for digit 7

Result of Experiment(3)

Recognition process in matlab for digit 3

CONCLUSION

• This is a simple and superior algorithm

• This algorithm can successfully detect printed assamese digits almost 100%.

• This algorithm can successfully detect assamese handwritten digits almost 80% in average.

• Recognition rate is not very satisfactory but for some assamese digits it is good (০,৮ and ৭ 96%).

• However by increasing alternate path recognition rate can be improved. This work is recommended as future work.

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Thank you for your time