Illuminant Multiplexed Imaging: Basics and Demonstration

We present a novel spectral imaging technique that allows multiple gray-scale images to be combined in a single hardcopy print. The images are individually revealed when the print is illuminated by suitably chosen light sources. In its basic form, the technique utilizes the complementary relation between cyan, magenta, and yellow colorants and narrow band red, green, and blue illuminants to combine and extract the images. Instead of the conventional color imaging scenario, where three-dimensional color attributes of a print are controlled under a wide-band illuminant using a set of colorants, in illuminant multiplexed imaging, one dimensional luminance attributes under two or more narrow-band illuminants are simultaneously controlled using the same colorants. We present a brief mathematical framework for illuminant multiplexed imaging and describe useful approximations that significantly simplify implementation. Several applications of the technology are presented.