ICIC Express Letters ICIC International ⓒ2010 ISSN 1881-803X Volume 5, Number 6, October 2014 pp. 1715–1720 This article was originally printed in 2014: Moritaka, K., and Kawano, T. (2014) Spectroscopic analysis of the model color filters used for computation of CIELAB-based optical logic gates. ICIC Express Letters, Part B: Applications 5(6): 1715-1720. Spectroscopic analysis of the model color filters used for CIELAB-based color computing models Kiyoshi Moritaka 1 and Tomonori Kawano 1,2 1 Faculty and Graduate School of Environmental Engineering, The University of Kitakyushu, Kitakyushu, Japan 2 University of Florence LINV Kitakyushu Research Center (LINV@Kitakyushu), Kitakyushu, Japan kawanotom@kitakyu-u.ac.jp Received October 2013 accepted January 2014 ABSTRACT. In the last two decades, we experienced the advancement of natural computing systems employing physical, chemical and biological properties as the direct media for manifesting the computation. Among such attempts, the studies focusing on the use of lights as key computation components in particular have attracted the attention by researchers and engineers since these studies are potentially applicable to the signal processing through optical interconnections between electronic devices. Previously, we have proposed novel CIELAB-based color computing model using printable and computable color codes aiming various applications such as development of optical logic gates. Our recent works included the use of CIELAB-coded colors on printed-papers or films to compute Boolean operations. In addition, colored reflectors were also used for conjunction, disjunction and/or masking of colors printed on the films. Above approaches provide an interesting unplugged color computing models by which Boolean operations of colors can be achieved simply by overlaying a color code-printed film over colored films, paper or reflectors. Through spectroscopic analysis, key optical properties of the color codes for Boolean operations were highlighted. The present work may allow us to develop the system using various light sources required for enhanced color reading. Furthermore, the likely applications can be found in the area of security, through ciphering and deciphering of color codes using the arrays of printed colors. Keywords: color barcode; natural computing; optical computing; printable memory 1. Introduction. In the last two decades, a number of researchers have been engaged in the study of natural computing systems that employ physical, chemical and biological properties as the direct media for manifesting the computation [1-3]. Among such attempts, the studies focusing on the use of lights as key computation components in particular have attracted the attentions by researchers and engineers since these studies are potentially applicable to the