In the 21st century, methods for translating additive colours as seen on screens (Red Green Blue (RGB)) into subtractive colours (Cyan Magenta Yellow Black (CMYK)) for industrial print are based on 4-colour halftoning. CMYK are so called process colours, used for printing on opaque substrates, from paper to glass and metal, when photomechanical reproduction is desired. These reproductions surround us, from images in books and magazines, on packaging to prints on clothing, homeware and advertising banners. Additive RGB colours are traditionally used in transmittance, i.e. in backlit applications, for example in mobile phones, laptops, tablets etc. SpectravalTM pearlescent pigments produced by Merck open the possibility of RGB, i.e. additive, colour printing on opaque substrates. We present here a characterisation of the optical features of these effect pigments and discuss print applications.
Susanne Klein, Carinna Parraman, Louis Voges, "How to print a rainbow" in Proc. IS&T Printing for Fabrication: Int'l Conf. on Digital Printing Technologies (NIP35), 2019, pp 52 - 55, https://doi.org/10.2352/ISSN.2169-4451.2019.35.52