Dewarping of camera-captured document images is one the important preprocessing steps before feeding them to a document analysis system. Over the last few years, many approaches have been proposed for document image dewarping. Usually optical character recognition (OCR) based and/or feature based approaches are used for the evaluation of dewarping algorithms. OCR based evaluation is a good meas...

Traditional OCR systems are designed for planar (dewarped) images and the accuracy is reduced when applied on warped images. Therefore, developing new OCR techniques for warped images or developing dewarping techniques are the possible solutions for improving OCR accuracy camera-captured documents. Among different types of dewarping techniques, curled textlines information based dewarping techn...

Dewarping of documents captured with hand-held cameras in an uncontrolled environment has triggered a lot of interest in the scientific community over the last few years and many approaches have been proposed. However, there has been no comparative evaluation of different dewarping techniques so far. In an attempt to fill this gap, we have organized a page dewarping contest along with CBDAR 200...

As compared to scanners, cameras offer fast, flexible and non-contact document imaging, but with distortions like uneven shading and warped shape. Therefore, camera-captured document images need preprocessing steps like binarization and textline detection for dewarping so that traditional document image processing steps can be applied on them. Previous approaches of binarization and curled text...

This paper proposes a novel stereo vision technique for top view book scanners which provide us with dense 3d point clouds of page surfaces. This is a precondition to dewarp bound volumes independent of 2d information on the page. Our method is based on algorithms, which normally require the projection of pattern sequences with structured light. We use image sequences of the moving stripe light...

The performance evaluation of dewarping techniques is currently addressed by concentrating in visual pleasing impressions or by using optical character recognition (OCR) as a means for indirect evaluation. In this study, the authors present a performance evaluation methodology that calculates a comprehensive evaluation measure which reflects the entire performance of a dewarping technique in a ...

In this paper, we propose a book dewarping model based on the assumption that the book surface is warped as a cylinder. This model extends the model proposed by Cao and makes Cao’s model a special case of our model. This extension removes the constraint of Cao’s model that the camera lens must be strictly parallel to the book surface, which is hard to make in practice, therefore enables a user ...

This paper presents a novel technique for efficient restoration of arbitrarily warped document images. Our aim is to recover document images that are mainly bounded volumes captured by a digital camera and suffer from non-linear warp. The proposed technique is applied on gray scale document images and is based on several distinct steps: an adaptive document image binarization, a text line and w...

Camera-captured document images usually contain two main types of marginal noise: textual noise (coming from neighboring pages) and non-textual noise (resulting from the page surrounding and/or binarization process). These types of marginal noise degrade the performance of the preprocessing (dewarping) of camera-captured document images and subsequent document digitization/recognition processes...