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Journal of Information Science and Engineering, Vol. 20 No. 4, pp. 771-782 (July 2004)

A Fast Finit-State Algorithm for Generating RGB
Palettes of Color Quantized Images*

Yu-Len Huang and Ruey-Feng Chang+
Department of Computer Science and Information Engineering
Tunghai University
Taichung, 407 Taiwan
+Department of Computer Science and Information Engineering
National Chung Cheng University
Chiayi, 621 Taiwan

On the WWW, the transmission time for videos and images impacts the performance of a web site. In order to reduce the bandwidth that is used to transmit images over the Internet, most image formats adopt only a limited number of colors used simultaneously to display color images on a video monitor. Hence, generating a good color palette for a color digitized image is an important task for Internet applications. In general, the Linde-Buzo-Gray (LBG) algorithm can be used to cluster a color digitized image in which each pixel is considered as a 3-dimension vector in an RGB color space for generating a color palette. The codebook generated by the LBG algorithm can be considered as the color palette for the color image. In order to obtain a good color palette, the LBG algorithm needs a large amount of computation time. In this paper, we propose a color finite-state LBG (CFSLBG) algorithm that reduces the computation time by exploiting the correlations of palette entries between the current and previous iterations. Instead of searching the whole color palette, the CFSLBG algorithm searches only a small number of colors that are very close to the training vector. Thus, the computation time for color quantization is reduced. The proposed approach generates RGB palettes efficiently with little sacrifice of quantized image quality. This paper describes the implementation of this work and simulation results.

Keywords: palettes generating, color quantization, LBG algorithm, finite-state algorithm, VQ

Full Text () Retrieve PDF document (200407_11.pdf)

Received January 21, 2002; revised January 21 & April 24, 2003; accepted May 8, 2003.
Communicated by Ming-Syan Chen.
* This work was supported by the National Science Council, Taiwan, R.O.C., under Grand NSC 91-2213-E-029-021.