Semi-Invariant Algorithm for Color to Gray and Back. - Takahiko Horiuchi; Fuminori Nohara; Shoji Tominaga (CIC, 2007)

Spectral reflectance estimation using a six-color scanner. - Shoji Tominaga; Satoshi Kohno; Hirokazu Kakinuma; Fuminori Nohara; Takahiko Horiuchi (Color Imaging: Displaying, Processing, Hardcopy, and Applications, 2009)

An accurate algorithm for color to gray and back. - Fuminori Nohara; Takahiko Horiuchi; Shoji Tominaga (ICIP, 2009)

Accurate reversible color-to-gray mapping algorithm without distortion conditions. - Takahiko Horiuchi; Fuminori Nohara; Shoji Tominaga (Pattern Recognit. Lett., 2010)