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Proceedings Paper

Comparison of lossless coding techniques for screened continuous-tone images
Author(s): Koen N.A. Denecker; Steven Van Assche; Wilfried R. Philips; Ignace L. Lemahieu
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Paper Abstract

Screening of color-separated continuous-tone photographic images produces large high-resolution black-and-white images (up to 5000 dpi). Storing such images on disk or transmitting them to a remote imagesetter is an expensive and time-consuming task, which makes lossless compression desirable. Since a screened photographic image may be viewed as a rotated rectangular grid of large half-tone dots, each of them being made up of an amount of microdots, we suspect that compression results obtained on the CCITT test images might not apply to high-resolution screened images and that the default parameters of many existing compression algorithms may not be optimal. In this paper we compare the performance of lossless one-dimensional general-purpose byte-oriented statistical and dictionary-based coders as well as lossless coders designed for compression of two- dimensional bilevel images on high-resolution screened images. The general-purpose coders are: GZIP (LZ77 by GNU), TIFF LZW and STAT (an optimized PPM compressor by Bellard). The non-adaptive two-dimensional black-and-white coders are: TIFF Group 3 and TIFF Group 4 (former published fax- standards by CCITT). The adaptive two-dimensional coders are: BILEVEL coding (by Witten et al.) and JBIG (latest fax- standard). First we compared the methods without tuning their parameters. We found that both in compression ratio (CR) and speed, JBIG (CR 7.3) was best, followed by STAT (CR 6.3) and BILEVEL coding (CR 6.0). Some results are remarkable: STAT works very well, despite its one- dimensional approach; JBIG beats BILEVEL coding on high- resolution images though BILEVEL coding is better on the CCITT images, and finally, TIFF Group 4 (CR 3.2) and TIFF Group 3 (2.7) can't compete with any of these three methods. Next, we fine-tuned the parameters for JBIG and BILEVEL coding, and this resulted in an increased compression ratio of 8.0 and 6.7 respectively.

Paper Details

Date Published: 16 September 1996
PDF: 11 pages
Proc. SPIE 2952, Digital Compression Technologies and Systems for Video Communications, (16 September 1996); doi: 10.1117/12.251263
Show Author Affiliations
Koen N.A. Denecker, State Univ. of Gent (Belgium)
Steven Van Assche, State Univ. of Gent (Belgium)
Wilfried R. Philips, State Univ. of Gent (Belgium)
Ignace L. Lemahieu, State Univ. of Gent (Belgium)

Published in SPIE Proceedings Vol. 2952:
Digital Compression Technologies and Systems for Video Communications
Naohisa Ohta, Editor(s)

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