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Handwritten Devanagari Character Recognition Using Modified Lenet and Alexnet Convolution Neural Networks

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Abstract

Despite many advances, Handwritten Devanagari Character Recognition (HDCR) remains unsolved due to the presence of complex characters. For HDCR, the traditional feature extraction and classification techniques are limited to the datasets developed in the respective laboratory that are not available publicly. A standard benchmarking dataset is not available for HDCR that helps to develop deep learning models. To progress the performance of HDCR, in this study, we produced a dataset of 38,750 images of Devanagari numerals, and vowels are generated and made publicly available for fellow researchers in this domain. This data is collected from more than 3000 subjects of different age groups. Each character is extracted by a segmentation technique proposed here, which is limited to this application. Experiments are conducted on the dataset; three different Convolution Neural Networks (CNN) architecture is developed. 1. CNN, 2. Modified Lenet CNN (MLCNN) and 3. Alexnet CNN (ACNN). A Modified LCNN is proposed by changing the architecture of Lenet 5 CNN. Regular Lenet 5 has \(\mathrm{tanh}(x)\) as its activation function. Since the Devangari characters are nonlinear, non-linearity is introduced in the Networks by using Rectified Linear Unit. This solves the problem of vanishing gradient problem by \(\mathrm{tanh}(x)\). We achieved a recognition rate of 96% on training data and 94% on unseen data using CNN. MLCNN obtained an accuracy rate of 99% and 94% with less computational cost. Whereas, ACNN attained a recognition rate of 99% and 98% on unseen data. A series of experiments were conducted on the data with different combination splits of data and found a minimum loss of 0.001%. Such developments fill a significant percentage of the huge gap between real-world requirements and the actual performance of Devanagari recognizers.

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Availability of data and material

The datasets generated during and/or analysed during the current study are available in the Mendeley repository, https://data.mendeley.com/datasets/pxrnvp4yy8/1

Code availability

The code that supports the findings of this study are available on request from the corresponding author. The code is not publicly available due to containing information that could compromise the privacy of research participants.

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Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

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Contributions

Duddela Sai Prashanth: Conceptualization, Methodology, Software, Visualization R Vasanth Kumar Mehta: Data curation, Writing—original draft, Data Analysis, Investigation. Kadiyala Ramana: Software, Validation, Editing. Vidya Charan Bhaskar: Supervision, Writing—review & editing.

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Correspondence to Vidhyacharan Bhaskar.

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Prashanth, D.S., Mehta, R.V.K., Ramana, K. et al. Handwritten Devanagari Character Recognition Using Modified Lenet and Alexnet Convolution Neural Networks. Wireless Pers Commun 122, 349–378 (2022). https://doi.org/10.1007/s11277-021-08903-4

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