We present a two-in-one visual cryptography (VC) scheme that not only shares an image of moderate confidentiality between two noisy transparencies, but also hides in these two transparencies a more confidential text file describing the image. None of the transparencies alone can reveal anything about the image or text. Later, people can view the image by simply stacking the two transparencies; on the other hand, after certain simple computations, the more confidential text data can also be extracted. We also introduce an alternative version in which the decoding of both the image and text requires no computer.
"Visual cryptography with extra ability of hiding confidential data," Journal of Electronic Imaging 15(2), 023020 (1 April 2006). https://doi.org/10.1117/1.2193912