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Proceedings Paper

Segmentation and automatic descreening of scanned documents
Author(s): Alejandro Jaimes; Frederick C. Mintzer; A. Ravishankar Rao; Gerry Thompson
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Paper Abstract

One of the major challenges in scanning and printing documents in a digital library is the preservation of the quality of the documents and in particular of the images they contain. When photographs are offset-printed, the process of screening usually takes place. During screening, a continuous tone image is converted into a bi-level image by applying a screen to replace each color in the original image. When high-resolution scanning of screened images is performed, it is very common in the digital version of the document to observe the screen patterns used during the original printing. In addition, when printing the digital document, more effects tend to appear because printing requires halftoning. In order to automatically suppress these moire patterns, it is necessary to detect the image areas of the document and remove the screen pattern present in those areas. In this paper, we present efficient and robust techniques to segment a grayscale document into halftone image areas, detect the presence and frequency of screen patterns in halftone areas and suppress their detected screens. We present novel techniques to perform fast segmentation based on (alpha) -crossings, detection of screen frequencies using a fast accumulator function and suppression of detected screens by low-pass filtering.

Paper Details

Date Published: 22 December 1998
PDF: 12 pages
Proc. SPIE 3648, Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts IV, (22 December 1998); doi: 10.1117/12.334597
Show Author Affiliations
Alejandro Jaimes, Columbia Univ. (United States)
Frederick C. Mintzer, IBM Thomas J. Watson Research Ctr. (United States)
A. Ravishankar Rao, IBM Thomas J. Watson Research Ctr. (United States)
Gerry Thompson, IBM Thomas J. Watson Research Ctr. (United States)

Published in SPIE Proceedings Vol. 3648:
Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts IV
Giordano B. Beretta; Reiner Eschbach, Editor(s)

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