A novel color-to-grayscale method is presented for converting color images to grayscale images by reducing dimensions. The proposed method converts three-dimensional (3-D) RGB color vectors into one-dimensional (1-D) grayscale values by projecting the 3-D vector into a two-dimensional (2-D) intermediate one followed by compressing the 2-D vector into the 1-D value. Characteristics of color are introduced to facilitate the final determination of the 1-D values in the reducing dimensions. The proposed method has the advantages of preserving chromatic contrasts, maintaining luminance consistency, and having a low computational cost. Furthermore, the proposed method has high resistance to artifacts, such as halos, which can occur when using local contents.
"Converting color images to grayscale images by reducing dimensions," Optical Engineering 49(5), 057006 (1 May 2010). https://doi.org/10.1117/1.3431688