Entropy Based Skew Correction of Document Images

Arvind, K.R.; Kumar, J. R. Harish; Ramakrishnan, A. G.

doi:10.1007/978-3-540-77046-6_61

Cited by 13 publications

(12 citation statements)

References 5 publications

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“…The angle with maximum standard deviation is taken as a skew angle of the document image. Arvind et al (2007) use inherited randomness in the Horizontal Projection profiles of a text block image, as the skew of the image varies. However, their technique can deal with the document skew up to ±10 • .…”

Section: Projection Profile Based Approachesmentioning

confidence: 99%

RETRACTED ARTICLE: Document image analysis: issues, comparison of methods and remaining problems

Saba

Sulong

2010

Artif Intell Rev

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Image analysis is an interesting research area with a large variety of challenging applications. Researchers have worked from decades on this topic, as witnessed by the scientific literature. However, document image analysis is the special case in image analysis as their spatial properties are different from natural images. Therefore, the main focus of this paper is to describe image denoising issues in general and document image issues in particular. Since the field of document processing is relatively new, it is also dynamic, so current methods have room for improvement and innovations are still being made. Several algorithms proposed in the literature are described. Critical discussions are reported about the current status of the field and open problems are highlighted. It is also demonstrated that, there are rarely definitive techniques for all cases of a certain problem. We surveyed the state of art, analyzed recent trends and tried to identify challenges for future research in this field.

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Section: Projection Profile Based Approachesmentioning

confidence: 99%

RETRACTED ARTICLE: Document image analysis: issues, comparison of methods and remaining problems

Saba

Sulong

2010

Artif Intell Rev

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“…An entropy based skew estimation technique has been presented by Arvind et al [4]. The idea incorporated in this approach is that the Horizontal Projection Profile (HPP) elements show a repetitive nature in case of non-skewed text block and hence the randomness associated with the HPP for a block increases with the variance in the skewness of the blocks.…”

Section: Introductionmentioning

confidence: 99%

A Fast Skew Correction Technique for Camera Captured Business Card Images

Mollah

Basu

Das

et al. 2009

2009 Annual IEEE India Conference

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Performance of an Optical Character Recognition engine may be affected if the images are skewed and distorted due to perspective projection. In this paper, a computationally efficient skew correction technique has been presented for extracted text regions from business card images. The skew angle is estimated by analyzing the bottom and/or top profiles (height/depth from a horizontal base line) of a text region. After rejecting some of the profile elements based on mean and mean deviation, three reference profile elements are chosen from which we get three skew angles. The average is considered as the computed skew angle. Besides being faster, it has an applicable accuracy and the effect of perspective distortion is made normalized. It is observed from the experiment that the average deviation of the skew corrected text lines, from the ground truth data, is within ±3 degree while the average processing time is between 17-110 milliseconds for 0.45-3.0 mega pixel images.

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“…The optimization of the cost function detects the text skew angle. The extension of this method is given in [3], by introducing the entropy concept. Furthermore, the combination of the vertical and horizontal projection profiles method is introduced in [25].…”

Section: Introductionmentioning

confidence: 99%

“…The aim of this paper is to describe an algorithm for the text skew estimation based on the entropy. Accordingly, we suggest the optimization of previously proposed entropy method [3], which leads to speeding up the algorithm by the factor up to 4 times. Furthermore, the method is extended by calculating entropy from vertical projection profiles, too.…”

Section: Introductionmentioning

confidence: 99%

“…It is similar to the one given in [25], which used both horizontal and vertical projection profiles to calculate the text skew of the image. However, our approach uses an entropy calculation instead of projection profile ones, which represents the extension to the method given in [3], [25]. The proposed combined entropy as well as each of the entropy algorithms is tested using a document database DISEC'13 during the experiment [24].…”

Section: Introductionmentioning

confidence: 99%

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Text Skew Detection Using Combined Entropy Algorithm

Brodić

Milivojević

2017

ITC

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This paper proposes the algorithm for text skew estimation based on the combined entropy calculation. The method consists of three steps. In the first step, it calculates the horizontal and vertical projection profiles. In the second step, the horizontal and vertical entropy for the rough angles is calculated. In the last step, the horizontal and vertical entropy calculation for the smooth angles is performed. The calculated entropy creates the two cost functions: horizontal and vertical. The position where each of cost functions has an absolute minimum represents horizontal and vertical estimated text skew angle. In the last step, it estimates the text skew angle as a mean of horizontal and vertical estimated text skew angles. The functionality, correctness and robustness of the proposed algorithm is investigated by the experiment, which is based on DISEC'13 document database. The obtained results are promising. They confirm that the method correctly estimates text skew angle.

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Entropy Based Skew Correction of Document Images

Cited by 13 publications

References 5 publications

RETRACTED ARTICLE: Document image analysis: issues, comparison of methods and remaining problems

RETRACTED ARTICLE: Document image analysis: issues, comparison of methods and remaining problems

A Fast Skew Correction Technique for Camera Captured Business Card Images

Text Skew Detection Using Combined Entropy Algorithm

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