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A Comparative Study on OCR using Super-Resolution for Small Fonts

  • Cho, Wooyeong (Department of Electronics Engineering, Kwangwoon University) ;
  • Kwon, Juwon (Department of Electronics Engineering, Kwangwoon University) ;
  • Kwon, Soonchu (Graduate School of Smart Convergence, Kwangwoon University) ;
  • Yoo, Jisang (Department of Electronics Engineering, Kwangwoon University)
  • Received : 2019.07.16
  • Accepted : 2019.07.27
  • Published : 2019.09.30

Abstract

Recently, there have been many issues related to text recognition using Tesseract. One of these issues is that the text recognition accuracy is significantly lower for smaller fonts. Tesseract extracts text by creating an outline with direction in the image. By searching the Tesseract database, template matching with characters with similar feature points is used to select the character with the lowest error. Because of the poor text extraction, the recognition accuracy is lowerd. In this paper, we compared text recognition accuracy after applying various super-resolution methods to smaller text images and experimented with how the recognition accuracy varies for various image size. In order to recognize small Korean text images, we have used super-resolution algorithms based on deep learning models such as SRCNN, ESRCNN, DSRCNN, and DCSCN. The dataset for training and testing consisted of Korean-based scanned images. The images was resized from 0.5 times to 0.8 times with 12pt font size. The experiment was performed on x0.5 resized images, and the experimental result showed that DCSCN super-resolution is the most efficient method to reduce precision error rate by 7.8%, and reduce the recall error rate by 8.4%. The experimental results have demonstrated that the accuracy of text recognition for smaller Korean fonts can be improved by adding super-resolution methods to the OCR preprocessing module.

Keywords

Korean OCR;Tesseract;Super-resolution;Text-recognition;and Deep-learning

Acknowledgement

Supported by : Kwangwoon University

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