Shi BAO^* and Go TANAKA^†

Graduate School of Natural Sciences, Nagoya City University, Nagoya 467-8501, Japan

(Received May 31, 2013; Accepted January 9, 2014)

In a color-to-gray conversion, which only considers lightness components, difference of colors are not appropriately reflected in monochrome images. Gooch et al. have proposed a color removal method that considers the differences of colors. Although the method can obtain good results in many cases, there is room for improvement. In this paper, a new color removal method that introduces a weight to Gooch's algorithm is proposed. In the proposed method, for combinations of colors of each pixel in an input image, weights are determined by distance in color space. In the proposed method, unimportant color combinations are not considered by weight and color information in an input image is appropriately reflected in a monochrome image. The validity of the proposed method is shown by experiments using some images.

Key words: color-to-gray conversion, color image, monochrome image, CIELAB color space, color difference

^*E-mail address: shibao@nsc.nagoya-cu.ac.jp
^†E-mail address: tanakago@nsc.nagoya-cu.ac.jp