Ordered halftone patterns in the original document interact with the periodic sampling of the scanner, producing
objectionable moir´e patterns. These are exacerbated when the copy is reprinted with an ordered halftone pattern.
A simple, small low-pass filter can be used to descreen the image and to correct the majority of moir´e artifacts.
Unfortunately, low-pass filtering affects detail as well, blurring it even further. Adaptive nonlinear filtering based
on image features such as the magnitude and the direction of image gradient can also be used. However, non
careful tuning of such filters could either cause damage to small details while descreeing the halftone areas,
or result in less descreening while sharpening small details. In this paper, we present a new segmentation-based
descreening technique. Scanned images are segmented into text, images and halftone classes using a
multiresolution classification of edge features. The segmentation results guide a nonlinear, adaptive filter to
favor sharpening or blurring of image pixels belonging to different classes. Our experimental results show the
ability of the non-linear, segmentation driven filter of successfully descreening halftone areas while sharpening
small size text contents.
KEYWORDS: Image segmentation, Halftones, Image processing algorithms and systems, Fuzzy logic, Scanners, Feature extraction, Detection and tracking algorithms, Linear filtering, Signal to noise ratio, Prototyping
In this paper, we introduce a new system to segment and label document images into text, halftoned images, and background using a modified fuzzy c-means (FCM) algorithm. Each pixel is assigned a feature vector, extracted from edge information and gray level distribution. The feature pattern is then assigned to a specific region using the modified fuzzy c-means approach. In the process of minimizing the new objective function, the neighborhood effect acts as a regularizer and biases the solution towards piecewise-homogeneous labelings. Such a regularization is useful in segmenting scans corrupted by scanner noise.
In this paper, we present a new system to segment and label the contents of scanned documents as either text or image, using a modified fuzzy c-means (FCM) algorithm. Each pixel is assigned a feature pattern extracted from the gray level distribution and computed at different scales. The invariant feature pattern is then assigned to a specific region using fuzzy logic. Our algorithm is formulated by modifying the objective function of the standard FCM algorithm to allow the labeling of a pixel to be influenced by the labels in its immediate neighborhood. The neighborhood effect acts as a regularizer and biases the solution towards piecewise-homogeneous labelings. Such a regularization is useful in segmenting scans corrupted by scanner noise.
Image resizing is an important operation that is used extensively in document processing to magnify or reduce images. Standard approaches fit the original data with a continuous model and then resample this 2D function on a few sampling grid. These interpolation methods, however, apply an interpolation function indiscriminately to the whole image. The resulting document image suffers from objectionable moire patterns, edge blurring and aliasing. Therefore, image documents must often be segmented before other document processing techniques, such as filtering, resizing, and compression can be applied. In this paper, we present a new system to segment and label document images into text, halftone images, and background using feature extraction and unsupervised clustering. Once the segmentation is performed, a specific enhancement or interpolation kernel can be applied to each document component. In this paper, we demonstrate the power of our approach to segment document images into text, halftone, and background. The proposed filtering and interpolation method results in a noticeable improvement in the enhanced and resized image.
In this paper, we present a new system to segment and label document images into text, halftone images, and background using feature extraction and unsupervised clustering. Each pixel is assigned a feature pattern consisting of a scaled family of differential geometrical invariant features and texture features extracted from the cooccurence matrix. The invariant feature pattern is then assigned to a specific region using a two-stage neural network system. The first stage is a self-organizing principal components analysis (SOPCA) network that is used to project the feature vector onto its leading principal axes found by using principal components analysis. Using the SOPCA algorithm, we can train the SOPCA network to project our feature vector orthogonally onto the subspace spanned by the eigenvectors belonging to the largest eigenvalues. By doing that we ensure that the vector is represented by a reduced number of effective features. The next step is to cluster the output of the SOPCA network into different regions. This is accomplished using a self-organizing feature-map (SOFM) network. In this paper, we demonstrate the power of the SOPCA-SOFM approach to segment document images into text, halftone, and background.
KEYWORDS: Surgery, 3D modeling, Image segmentation, Visualization, Magnetic resonance imaging, Picture Archiving and Communication System, Medical imaging, Computed tomography, Computer simulations, Brain
The growing scientific knowledge and rapid progress in medical imaging techniques has led to an increasing demand for better and more efficient methods of remote access to high-performance computer facilities. This paper introduces a web-based telemedicine project that provides interactive tools for surgical simulation and planning. The presented approach makes use of client-server architecture based on new internet technology where clients use an ordinary web browser to view, send, receive and manipulate patients' medical records while the server uses the supercomputer facility to generate online semi-automatic segmentation, 3D visualization, surgical simulation/planning and neuroendoscopic procedures navigation. The supercomputer (SGI ONYX 1000) is located at the Computer Vision and Image Processing Lab, University of Louisville, Kentucky. This system is under development in cooperation with the Department of Neurological Surgery, Alliant Health Systems, Louisville, Kentucky. The server is connected via a network to the Picture Archiving and Communication System at Alliant Health Systems through a DICOM standard interface that enables authorized clients to access patients' images from different medical modalities.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.