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Proceedings Paper

Pixel bit-depth increase by bit replication
Author(s): Robert A. Ulichney; Shiufun Cheung
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Paper Abstract

In many applications, such as inverse dithering, it is necessary to increase the pixel bit-depth of images by expanding q-bit integer values to m-bit integer values (m greater than q). This paper describes a simple and efficient method that uses bit replication, instead of conventional multiplication, to achieve this expansion. First, we show that the optimal number of repetitions is given by ceiling (m/q) and that the method is equivalent to multiplication by the ideal gain when m/q is an integer. We then demonstrate that, in the case where m/q is not an integer, truncating the fraction bits to the right of the decimal point will lead to zero average error. The paper also includes two suggestions for implementing the bit-replication process, both of which have a vast complexity advantage over a multiplier. Two examples are given at the end to illustrate the bit- replication process in action.

Paper Details

Date Published: 2 January 1998
PDF: 10 pages
Proc. SPIE 3300, Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts III, (2 January 1998); doi: 10.1117/12.298285
Show Author Affiliations
Robert A. Ulichney, Digital Equipment Corp. (United States)
Shiufun Cheung, Digital Equipment Corp. (United States)

Published in SPIE Proceedings Vol. 3300:
Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts III
Giordano B. Beretta; Reiner Eschbach, Editor(s)

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