Legibility of compressed document images at various spatial resolutions

Robert C. Kidd; Charles Martin Zalinski; Jerome I. Nadel; Robert D. Klein

doi:10.1117/12.28025

1 February 1991 Legibility of compressed document images at various spatial resolutions

Robert C. Kidd, Charles Martin Zalinski, Jerome I. Nadel, Robert D. Klein

Proceedings Volume 1454, Beam Deflection and Scanning Technologies; (1991) https://doi.org/10.1117/12.28025
Event: Electronic Imaging '91, 1991, San Jose, CA, United States

Abstract

Digital images of business and financial documents are replacing paper and microfilm in numerous applications. System bandwidth limitations usually necessitate data-compression of such images. Another way to decrease the bandwidth requirement for each image is to reduce the spatial resolution of the image, thereby reducing the total number of pixels which must be stored or transmitted. In this paper, the authors investigate the combination of spatial resolution reduction with the evolving ISO/JPEG grayscale image-compression standard. Both resolution reduction and ISO/JPEG data-compression cause distortion of the decompressed image with respect to the original. The system designer has some flexibility in allocating this distortion to each of the processes. The authors have conducted extensive testing to determine the best such allocation. Results of these tests indicate that legibility depends principally on compressed size. In particular, legibility is directly proportional to compressed size. The effects of spatial resolution on legibility are secondary. One such effect is a decrease in legibility with increasing spatial resolution as packet size is held constant at comparatively small values. Taken together, these results argue that the best legibility for document images compressed with the ISO/JPEG draft standard is obtained at the lowest adequate spatial resolution.

Citation Download Citation

Robert C. Kidd, Charles Martin Zalinski, Jerome I. Nadel, and Robert D. Klein "Legibility of compressed document images at various spatial resolutions", Proc. SPIE 1454, Beam Deflection and Scanning Technologies, (1 February 1991); https://doi.org/10.1117/12.28025

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