Bret:
I'm still interested in this. Did you just happen to have a pair of "colored lens glasses" laying around that you were experimenting with hidden patterns? Where do the glasses come in with your experiment?
I found a reference to Red Reveal and a company called Visionet New Media, in the UK. They appear to be reorganizing and information about the product is scarce.
I've learned that it can be done with two metameric inks, but that will be too expensive, and unlike the current product that a certain customer likes. That would seem to take it out of the digital printing window, and sounds expensive. I want to do it on an Indigo because the run lengths are small but numerous.
We'll keep the cause alive, and let me know if you have any other ideas. Or others on the planet that are interested/intrigued.
John Lind
Cranberry Township, PA
724-776-4718