Unphotogenic Light
Evaluation and Detail of the High-Speed Projection Method
to Prevent Secret Photography with Small Cameras
Ippei Suzuki, Shinnosuke Ando, Yoichi Ochiai
University of Tsukuba, Strategic Research Platform towards Digital Nature Powered by Pixie Dust Technologies, Inc.
Session 70 - Projection: Screen Technology

2

3
Introduction Content Protection on the Screen
Protecting images projected on a screen is a difficult problem

4
Introduction Content Protection on the Screen
Copy
Contents is protected by
data copy guard techniques
People can take contents
shown on the screenbut
Protecting images projected on a screen is a difficult problem

Examples of the content captured by taking the screen
5
*This image is only for illustration purposes, NOT actual result from the video-sharing services.

Visible
to
Human Eyes
Recordable
by
Cameras≒
6

7

8
Introduction Practical Stories of the Proposed Method
When you would like to protect this image
from secret photography...
Situation

9
Introduction Practical Stories of the Proposed Method
Solution A:
Visible Watermarks / Protection Marks
CONFIDENTIAL
COPYRIGHT
NO PHOTOS

CONFIDENTIAL
COPYRIGHT
NO PHOTOS
10
Introduction Practical Stories of the Proposed Method
Bad Experience for Visitors… 🤔
Solution A:
Visible Watermarks / Protection Marks

Security Check Area
11
Introduction Practical Stories of the Proposed Method
Security
Visitor Visitor’s Bag
Solution B:
Confiscate Camera Devices
Confiscate Camera Devices

12
Introduction Practical Stories of the Proposed Method
Visitor
Security
Don’t use cameras!!!
Solution B:
Confiscate Camera Devices
Security can orally warn overlooked cameras

13
Introduction Practical Stories of the Proposed Method
Visitor’s
Pocket
Visitor
Secret Camera
e.g., Pen-Shaped Small Camera
They can take photos 😭
Solution B:
Confiscate Camera Devices

14
Introduction Target in This Study
Our Target
Kinds of the situation protecting the content
Confiscate Camera Devices
but contents are secretly captured
CONFIDENTIAL
COPYRIGHT
NO PHOTOS
Visible Watermarks
not only camera, but also people

15
Introduction Target in This Study
Kinds of the camera which criminals may use
Our Target
“Spy Car Remote Control Camera”
by DigitPedia Website (CC BY 2.0, Color Modified)
“Sony Xperia Z3 smartphone” by John Jones
(CC BY 2.0, Color Modified)“Google Glass” by Kārlis Dambrāns (CC BY 2.0, Background deleted) “Sony Alpha A77” by SkywalkerPL (CC BY 3.0)
Not considered
in ours
Camera Camera
Spy Camera Smart Glass Smartphone DSLR

16
Introduction Goal
Human eyes can see Cameras can NOT see
= Unphotogenic

“Unphotogenic” — Looking non-attractive in photographs or on film
— Not appear in photos as they really are in real life
17

18

<
Temporal Resolution
19

20
Related Work
VRCodes [2]Detection of Imperceptible On-Screen Markers
with Unsynchronized Cameras [1]
[1]
[2]
Invisible Markers on Screen
Sampaio Luiz, Yamada Yoshio, Yamamoto Goshiro, Taketomi Takafumi, Sandor Christian, and Kato Hirokazu.
Detection of imperceptible on-screen markers with unsynchronized cameras. IPSJ SIG Notes. CVIM, 2015(64):1–4, jan 2015.
Grace Woo, Andy Lippman, and Ramesh Raskar. Vrcodes: Unobtrusive and active visual codes for interaction by exploiting rolling shutter. In Proceedings of the 2012 IEEE
International Symposium on Mixed and Augmented Reality (ISMAR), ISMAR ’12, pages 59–64, Washington, DC, USA, 2012. IEEE Computer Society.

21
Afterimage
An impression of a vivid sensation retained after the stimulus has ceased

22
Method Approach

23
Method Approach
Divide Image
Switch
in High Refresh Rate

24
Method Theory and Effect of the Proposed System

25
Implementation Projector
DLP® LightCrafter™ 4500 EVM
Texas Instruments
DMD
912 × 1140 diamond pixel
0.45-inch WXGA DMD
Resolution Up to 1280 × 800
Light source RGB LED light engine
with 150 lumen light output
Max video speed Up to 120 Hz
Max pattern speed
Up to 4225 Hz binary pattern
Up to 120 Hz 8-bit grayscale pattern

26
210mm
297 mm
Projector
Camera
Screen

27
Evaluation Patterns of division
Plasma effect
Patterns of division in evaluation
Reference: Lode's Computer Graphics Tutorial
http://lodev.org/cgtutor/plasma.html

28
Result Evaluation from Camera Vision
DSLR
Smartphone
Variable Aperture
Fixed Aperture
SS 1/15, F1.8
Canon EOS Kiss X4
w/ SIGMA 17-50mm F2.8 EX DC OS HSM
All photos were taken by ISO 100, 50mm.
Apple iPhone 7
w/ App “ProShot” by Rise Up Games LLC.)
All photos were taken by F/1.8, ISO 20, 28mm.
SS 1/30, F1.8 SS 1/120, F1.8 SS 1/160, F1.8
**Focal lengths are the corresponding value for a 35-mm Film.
SS 1/15, F18 SS 1/30, F13 SS 1/125, F5.6 SS 1/160, F5.6
*Pictographs of shutter speeds and apertures indicate the rough value.
Smartphones cannot change the aperture
Aperture (F-stop)Shutter speed

29
Method Theory and Effect of the Proposed System
Don’t use cameras!!!
Combination of the human power and our system
Picture which our system applied
Visitors cannot take photos of the picture!

Global ShutterRolling Shutter (popular)
30
Result Evaluation from Camera Vision (other smartphones & cameras)
Apple Inc.
iPhone 7
G8142; Sony Mobile Communications Inc.
Xperia XZ Premium
5040o; TCL Communication Ltd.
Alcatel OneTouch Flint
PRA-LX2; HUAWEI Technologies Co.
HUAWEY nova lite
DSC-W110, Sony Corp.
Cyber-shot
Not affected by the type of the image sensor
*Photos are taken with the default application, automatic mode.

31
Application Other Examples than Displaying Divided Images
EXIT
$10
Theme Park
Photo by Ted Murphy (CC BY 2.0) Photo by Ted Murphy (CC BY 2.0)
Result
Overlay onto the photos sold near the exit of the attraction

32
Application Other Examples than Displaying Divided Images
Museum
Result
Overlay onto the artworks
Projector
Artwork

33
Discussion & Future Work Robustness
Reconstructable from multiple photographs?
All parts of the original image are needed

34
Discussion & Future Work Flicker
*This video is for illustration purposes.
When a saccade occurs
on human's eyes or when human blink,
people sometimes perceive flicker.
Tradeoffs between
the strength of the system’s resistance to flicker
and an acceptable shutter speed (slowness).
Not suitable for extended viewing of media?
Optimization of patterns of division?

35
Discussion & Future Work Quality of the Display
The brightness of each pixel becomes 1/n of the normal projection.
But we need enough brightness of the screen to affect our system into photograph.
Normal
Ours
Time
Brighter projectors?
N times division
1/N brightness Observed

36

37
Contact: 1heisuzuki@digitalnature.slis.tsukuba.ac.jp
Unphotogenic Light
Evaluation and Detail of the High-Speed Projection Method
to Prevent Secret Photography with Small Cameras
Ippei Suzuki, Shinnosuke Ando, Yoichi Ochiai
University of Tsukuba, Strategic Research Platform towards Digital Nature Powered by Pixie Dust Technologies, Inc.
Questions?
Ippei Suzuki Shinnosuke Ando Yoichi Ochiai