Super Secret Spy Message

umlautthoni's picture

I have been trying to find any information on how to print secret messages. The concept is simple, print a message in red with a blue pattern over the top to disguise the message. The recipient would then use a blue-filmed set of glasses to filter the blue pattern and reveal the message. Over the years, I have subscribed to over a half dozen different design magazines and could have sworn I saw a how to article on this very subject. But, wouldn't you know it, when I actually want to attempt this technique, I can't find the article.

Thanks for any assistance you may provide.


Michel Boyer's picture

Here is a relevant reference:

Young-Chang Hou, Visual cryptography for color images, Pattern Recognition, Volume 36, Issue 7, July 2003, Pages 1619-1629, ISSN 0031-3203, DOI: 10.1016/S0031-3203(02)00258-3.
Keywords: Visual cryptography; Halftone technology; Color decomposition; Information sharing

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