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Unphotogenic Light
High-Speed Projection Method to Prevent
Secret Photography by Small Cameras
Ippei Suzuki Undergraduate Student, University of Tsukuba
Yoichi Ochiai Assistant Professor, University of Tsukuba
Emerging Technologies Talk: Magic of Light

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Introduction Content Protection on the Screen
Content Protection on the Screen = Difficult Problem

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Introduction Content Protection on the Screen
Content Protection on the Screen = Difficult Problem
Copy
Analog/Digital Copy Guard Techniques
They can take photos !

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Introduction Content Protection on the Screen
Visible
to
Human Eyes
Recordable
by
Cameras

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Introduction Content Protection on the Screen

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

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

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

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

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

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

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Introduction Target in This Study
Our Target
http://amzn.asia/etlTVOj “Google Glass” by lawrencegs (CC BY 2.0) “iPhone 7 Plus” by Kārlis Dambrāns from Latvia (CC BY 2.0) “Sony Alpha A77” by SkywalkerPL (CC BY 3.0)
Not considered in ours
Kinds of the camera which criminals may use
(Pen-shaped
camera)

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Introduction Goal
Human eyes can see Cameras cannot see
= Unphotogenic

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Introduction Solution
<
Temporal Resolution

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Related Work
VRCodes [Woo et al. 2012]Detection of Imperceptible On-Screen Markers
with Unsynchronized Cameras
[Sampaio et al. 2015]
Invisible Markers on Screen

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Method Apploach
Afterimage Effect
An impression of a vivid sensation retained after the stimulus has ceased

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Method Apploach

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Method Apploach
Divide Image
Switch
in High Refresh Rate

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Method Theory and Effect of The proposed System
Frame DivisionSource Image
Frame Period
Suitable Shutter Speed & Timings
Time
Projected
Image
Flame No.
Assigned
0 1 2 3
Recorded
Image
Shutter
Projection Period
Incomplete Shutter Speed & Timings Examples

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Result Evaluation from camera vision
DSLR
Smartphone
Variable Aperture
Fixed Aperture
SS 1/30, F20
SS 1/45, F2.2
SS 1/125, F10 SS 1/320, F6.3
SS 1/1000, F2.2SS 1/160, F2.2
Apple iPhone 6, with App “ProShot” by Rise Up Games LLC. All photos were taken by F/2.2, Not changeable the F-stops value.
Canon EOS Kiss X4 with TAMRON B005 17-50 mm F/2.8, All photos were taken by ISO 100
Cannot change the apearture

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Method Theory and Effect of The proposed System
Visitor
Security
Don’t use cameras!!!
Combination of the human power and our system

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Result Evaluation from camera vision
kvy37; Kyocera Corp.
Qua phone
ZE551ML; ASUSTeK Computer Inc.
ZenFone 2
A500KL; ASUSTeK Computer Inc.
ZenFone 5
SO-01F, Sony Corp.
Xperia Z1
DSC-W110, Sony Corp.
Cyber-shot
CCD Image Sensor
(Global Shutter)
*Photos are taken with the default automatic mode.

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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

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Application Other examples than displaying divided images
Museum
Result
Overlay onto the artworks
Projector
Artwork

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Discussion Limitation and Future Work
Avoidance by merging multiple photos
Color image
Optimization the division pattern
Applicability for the video contents

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FAQ
2. Could the system show the video as projection image?
3. Could the system show the video as blurred patterns?
1. Can I use my own logo for division pattern?
4. Can the system increase the number of the division?
Unphotogenic Light
Please visit our booth! and let’s try to take photo by your smartphone!!
— Yes in principle, under development
— Difficult. Changes of the division pattern are easily perceived by people.
— Yes, 2-bit image only because it should divide areas
— Yes, but decrease the brightness of the screen