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Proceedings Paper

Compression of screened halftone image using block prediction
Author(s): Xiaofan Feng
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Paper Abstract

Binary image compression is different from contone image compression. Binary image compression ratio varies greatly with halftoning algorithm as well as image type. Most binary compression methods cannot efficiently compress images halftoned using frequency modulation (FM) screening or error diffusion. The blue noise characteristic of the output pattern makes all run-length based compression algorithms ineffective. In this paper, we describe a method that combines prior information about the halftone screen used in the halftone process with local statistics to improve the prediction of the FM screened halftone image. The binary image is first broken into sub-blocks and the mean of each block is calculated. This block mean and the halftone screen are used to generate a predicted image. A residual image, the difference between the predicted image and the original halftone image, can be constructed by performing an exclusive OR between the original image and the predicted image. Since there is strong correlation between this predicted pattern and the original halftone image, the residual image consists mainly of zeros. The residual image can then be compressed with run-length encoding algorithms. We applied this method to a number of test images with both photo and text content; the compression ratio is improved by up to a factor of 10 as compared to a standard run-length encoding algorithm.

Paper Details

Date Published: 28 December 2001
PDF: 7 pages
Proc. SPIE 4663, Color Imaging: Device-Independent Color, Color Hardcopy, and Applications VII, (28 December 2001); doi: 10.1117/12.452995
Show Author Affiliations
Xiaofan Feng, Sharp Labs. of America (United States)

Published in SPIE Proceedings Vol. 4663:
Color Imaging: Device-Independent Color, Color Hardcopy, and Applications VII
Reiner Eschbach; Gabriel G. Marcu, Editor(s)

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