Glow Code developed out of experiments with screen printing phosphorescent coatings on fabric. I observed an unusual response in the coatings to computer screens. Different colors caused the fabric to glow at different strengths, and it was unrelated to the color brightness. Using the wavelength of light rather than its perceived brightness, I created a system for encoding messages in computer screens.
This technique was used initially for fabrics. Recently, I partnered with Jonathan Bobrow to develop Glow Code greeting cards. We are using Processing to write a script that automatically encodes user-uploaded messages.