1. A method of creating a grayscale image using an image processing apparatus (IPA), the method comprising: converting, in a color image consisting of a plurality of pixels, a pixel value of each pixel in a RGB color space into a pixel value in a new color space through linear conversion; extracting, using the IPA, color information using the pixel value in the new color space; calculating, using the IPA, a luminance change amount of each pixel using the extracted color information; and calculating, using the IPA, a luminance value for the grayscale image by combining an original luminance value of each pixel and the luminance change amount, and creating the grayscale image according to the calculated luminance value, wherein the extracted color information reflects the features of colors in the reddish colors and colors in the bluish colors to make colors in the reddish colors brighter in the grayscale image than colors in the bluish color.