Practical Application of Visual Illusions: errare humanum est

Some practical applications of visual illusions are explored for both real and virtual environments - with an emphasis on the cryptographic domain in which illusions may be employed to distinguish between humans and non-human agents. Non-human agents are unlikely to suffer the same visual illusions as we do. A Turing test differs from our approach since it relies on human-like ability rather than the characteristic human failing intrinsic in visual illusions:- "To err is human...". The CAPTCHA system for on-line challenge-based authentication can be extended so as to exploit visual illusions. In particular we consider PIX the picture-based system, and illustrate a simple steganographic application. The utility of both are discussed.

@Article{BC05,
  author       = {Brelstaff, G. and Chessa, F.},
  title        = {Practical Application of Visual Illusions: errare humanum est},
  journal      = {APGV '05 Proceedings of the 2nd symposium on Applied perception in graphics and visualization},
  pages        = {161},
  year         = {2005},
  publisher    = {ACM Inc},
  note         = {26th - 28th August, La Coruna, Spain},
  issn         = {ISBN:1-59593-139-2},
  doi          = {10.1145/1080402.1080441},
  url          = {https://publications.crs4.it/pubdocs/2005/BC05},
}