Unphotogenic Light Key Image

Unphotogenic Light

High-Speed Projection Method to Prevent Secret Photography
SID Symposium Digest of Technical Papers 2018


Protecting images projected on a screen is a difficult problem. Although protection techniques for digital copies have been discussed for many years, recordable content projected by general display techniques (e.g., LCDs, projectors) is not only visible to humans but can also be captured by cameras. In these cases, that which is "visible to human eyes" is nearly the same as being "recordable by a camera". Thus, projected recordable content is sometimes secretly captured by small cameras even when protection techniques against digital copies have been adopted. How can we fundamentally prevent content from secret photography?


We focused on the difference between human and camera vision systems. Unlike cameras, humans cannot recognize the high-speed changes of light. We divide the image into smaller parts and project each part in succession over the same projection periods. That projected image becomes human eyes can see but cameras can only capture as an incomplete frame.


Supplemental Video (SIGGRAPH 2017 Posters)

Presentation Slide (2018 SID Display Week Symposium, Ippei Suzuki)

Project Members

Ippei Suzuki
Digital Nature Group,
University of Tsukuba (JP)
Shinnosuke Ando
Digital Nature Group,
University of Tsukuba (JP)
Yoichi Ochiai
Digital Nature Group,
University of Tsukuba (JP)
Pixie Dust Technologies, Inc. (JP)