Pixel bit-depth increase by bit replication

Robert A. Ulichney; Shiufun Cheung

doi:10.1117/12.298285

2 January 1998 Pixel bit-depth increase by bit replication

Robert A. Ulichney, Shiufun Cheung

Proceedings Volume 3300, Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts III; (1998) https://doi.org/10.1117/12.298285
Event: Photonics West '98 Electronic Imaging, 1998, San Jose, CA, United States

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.

Citation Download Citation

Robert A. Ulichney and Shiufun Cheung "Pixel bit-depth increase by bit replication", Proc. SPIE 3300, Color Imaging: Device-Independent Color, Color Hardcopy, and Graphic Arts III, (2 January 1998); https://doi.org/10.1117/12.298285

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