International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 11 Issue: 11 | Nov 2024
p-ISSN: 2395-0072
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Discrete Topological Derivative Based Show-Through Noise Reduction in Scanned Document Images N. Habibunnisha1, M. Geethalakshmi2 and D. Nedumaran3* 1,3Central Instrumentation and Service Laboratory, University of Madras, Guindy Campus,
Chennai 600 025, Tamil Nadu, India
2 Department of Mathematics, Queen Mary’s College, Chennai 600 004, Tamilnadu, India
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Abstract - The interdisciplinary approach of fusing ideas
information to realize our history, culture, language, evolution of society, and many more [1]. During the digitization process, the scanned digital data contains various types of noises such as margin noise, ruled line noise, clutter noise, non-uniform illumination noise, uneven contrast, interfering strokes, background spots, showthrough effect etc. These noises will affect the quality of the document image as well as readability [2]. Among these noises, the show-through noise is one of the major artifacts that affects the quality and readability of the document. Therefore, these noises should be removed without the loss of details in the scanned original documents. Show-through effect is one of the document image noises which present during the document digitization process due to document ageing, ink seepage, thickness/quality of the paper, and scanning device. In a scanner, when the single side printed/handwritten document is scanned, the light exposes to the paper transmits through the document medium and reflects back by the backing of the scanner. The reflected light receives the front-side information by the detector and sent for the display and storage section. But, in the case of double-side printed document scanning, the back-side of the document information merges with the front-side of the document information is known as ‘show-through’ or ‘bleedthrough’ or ‘back-to-front interference’ [3]. This interference makes the reader uncomfortable in understanding and complexities in further processing tasks like automatic character recognition. Several denoising and binarization techniques were investigated by many researchers for removing the document degradations from scanner or camera captured images. Various image enhancement techniques such as non-registration [4, 5], registration-based [6, 7], histogram-based [8], thresholding-based [9-11], Genetic algorithm-based [12], and wavelet-based filtering [13] had been implemented to ameliorate the quality and readability of the scanned document images. Still this issue is prevailing as a challenging task and researchers in this area have been endeavoring with multidisciplinary approach of transforming the mathematical ideas established in other fields to solve this kind of document image processing tasks. As a consequence of this effort, a novel structural mechanics concept namely, discrete topological derivative (DTD) was experimented in this research paper for filtering the showthrough noise in combination with a binarization technique to enhance the quality and readability of the scanned document images.
from different domains with an objective of optimized results is a recent trend in the research areas of image processing. One such attempt was experimented in this study by combining structural mechanics concept of Discrete Topological Derivative (DTD) with Otsu binarization method to remove the show-through existing in the scanned document images. The Otsu binarization method was chosen through a comparative study with other traditional binarization method. The proposed method DTD-cum-Otsu was implemented in scanned document images and compared with other six stateof-the-art techniques such as Wiener, Bilateral, Median, Gabor, Homomorphic and Perona-Malik. The algorithms developed for the proposed study was tested in more than 150 scanned document images collected from the databases viz., DIBCO2013, DIBCO2014 and Nabuco dataset-2 and classified into three groups such as lightly-affected (LA), moderatelyaffected (MA) and strongly-affected (SA) show-through noisy images. The effectiveness of the proposed DTD-cum-Otsu method was assessed through visual inspection and quality metrics like PSNR, MSE, NAE, NCC, AD, F-measure, pseudo-Fmeasure, DRD, NRM and MPM. The results of this study reveal that the proposed method is the optimum technique to remove the show-through noise effectively and retaining the useful information without distortion. Further, the execution speed of the proposed method is within the range of real-time application requirements. Thus, the outcome of this study exhibits the glimpse of hope on the multidisciplinary approach of solving potential real-life problems. Key Words: Show-through, Binarization, Image denoising, Diffusion, image enhancement, Quality metrics, DTD, Otsu.
1. INTRODUCTION In recent years, most of the important documents are being converted into digital formats for preserving them from aging, mutilation, spoilage, accidental damages, etc. Further, these scanned documents in the digital format have several advantages like security through encapsulation, e-exchange via digital communication, future reference through archiving, e-verification using authentication, etc. These records include ancient historical documents, government/official documents, ancient palm leaves collections, medical hints, etc., which bring lot of useful
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