Retinal Viewfinder - HCI International 2022 #HCII2022 (Oral presentation by Ippei Suzuki)

© Research and Development Center for Digital Nature
Retinal Viewfinder:
Preliminary Study of Retinal Projection-Based Electric Viewfinder for Camera Devices
Ippei Suzuki, Yuta Itoh, Yoichi Ochiai
Research and Development Center for Digital Nature, University of Tsukuba, Japan

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2
Background Photography Process
Adjust parameters Preview Take the photograph
Main Steps of Photography

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3
Background Preview Hardware Equipped on Camera Devices
Image: https://www.sony.jp/ichigan/products/ILCE-7SM2/index.html
Viewfinder
Display Screen

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4
Background Advantage of Viewfinders
Advantages of Viewfinders
cf. Display Screen
Blocking surrounding light
Stabilizing the camera

by bracing it against their face

& keeping their arm close to the body
Concentration on taking photos

by restricting the field of view

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5
Background Commercially Available Viewfinders
ɹImage (Left):https://dc.watch.impress.co.jp/docs/review/pentax100/1207316.html

Image (Right): https://cweb.canon.jp/eos/lineup/rp/feature-reliability.html
Optical Viewfinder
OVF
Ready-to-Use Viewfinders
*SLR
Electronic Viewfinder
EVF
Mirror
Pentamirror Display

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Background Di
ff
iculty of Viewfinder for People w/ Bad Eyesight
Image (Left): https://news.mapcamera.com/maptimes/cameratechiquevol16/
Di
ff
iculty of Viewfinder for People w/ Bad Eyesight
Limited range of diopter adjustment Colliding the glasses

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Introduction Proposed System
R-EVF
Retinal Projection-Based Electric Viewfinder

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Introduction Retinal Projection in the field of HMDs
Image (Left): https://www.moguravr.com/retissa-display/

Image (Right): https://prtimes.jp/main/html/rd/p/000000001.000060779.html
Retinal Projection
e.g., RETISSA Display
Providing a large depth of field projection enables one to focus on the displayed image easily

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9
Introduction A
R-EVF NR-EVF
Normal
Bad Eyesight*
*Taken with an incorrect focus target to simulate the vision of a person with bad eyesight.
 
**This image is only for illustration purposes of bad eyesight. Image looks di
ff
erent from actual view due to the shooting environment.

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1
0
Retinal Projection System
Camera

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1
1
Summary of Contribution
1. A method of building the R-EVF prototype

2. Investigations of the e
ff
ects of
 
using the prototype through a user study

3. Discussions of the results and
 
limitations of the current prototype.

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2
Implementation

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3
Implementation
Proposed
R-EVF Setup NR-EVF Setup

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4
© Research and Development Center for Digital Nature Image: https://www.amazon.co.jp/dp/B07KXLKZX4
Implementation Projector
HD Pico Laser Projector HD301
Ultimates, Inc.
Type of Display
Micro-electro-mechanical systems
(MEMS) mirror
Resolution 1280 × 720 pixels
Light source
RGB Laser
 
with 20 lumen (±10%) light output
Contrast Ratio 5000:1
Max video speed 60 Hz
Same projectors are used for both R-EVF and NR-EVF

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5
Implementation
Yoichi Ochiai et al.
 
Make Your Own Retinal Projector: Retinal Near-eye Displays via Metamaterials.
 
SIGGRAPH 2018 Emerging Technologies
R-EVF Optical Setup Reference

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6
Implementation Retinal Projection-Based Electric Viewfinder
R-EVF Setup
Projector
ND**
*DCRA: Dihedral corner reflector array **ND: Filter for reducing intensity
DCRA*
Lens Mount w/o Lens
Viewing Position

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1
7
Implementation Non-retinal Projection-Based Electric Viewfinder
Projector
Screen
Half-Mirror
Lens Mount w/ Lens
Viewing Position
NR-EVF Setup

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8
Implementation
Projector
ND
DCRA
Lens Mount w/o Lens
Viewing Position
Projector
Screen
Half-Mirror
Lens Mount w/ Lens
Viewing Position

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1
9
Implementation
Projector
ND
DCRA
Lens Mount w/o Lens
Viewing Position
Projector
Screen
Half-Mirror
Lens Mount w/ Lens
Viewing Position

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0
Implementation
R-EVF Vision NR-EVF Vision

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1
User Study

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2
User Study
Purpose
To explore the e
ff
ectiveness of our method

on focusing task when photography
Participants
12 Participants | 19-30 years old
All participants used a visual aid

4 participants first-time users of cameras w/manual focus

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3
User Study
Conditions
Video Camera
Camera
EVFs
Enclosure
Target Object Monitor

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4
User Study
Conditions Target Subjects
IEEE Reflection Target Drawing Mannequins
Camera
30
0 Unit: cm
100 150 200

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5
User Study
Conditions EVFs
Target Object
Camera
EVF

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6
User Study
Conditions Parameter Participants could change
Focus Ring
Face (Eye) Position
Fixed: Camera Position, Exposure, Viewfinder Position, Lighting…
Chin Rest (only for R-EVF)

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User Study
Conditions
Visual Aid
Viewfinder
R-EVF NR-EVF
w/
w/o
R-EVF
R-EVF
NR-EVF
NR-EVF

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8
User Study
Procedure Preparation
1. Quick eye test & Eye dominance test
 
2. Questionnaires e.g., daily photograph activity

3. Instruction on how to use EVFs
*Used to view EVFs

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9
User Study
Procedure For Each Condition
1. The experimenter set the camera’s focus
 
to the minimum focusing distance

2. Participants were asked to focus
 
on each subject using a viewfinder

3. While keeping the focus setting
 
the experimenter pressed the shutter
 
which was set to a 2-second delay self-timer
*1 photo was taken per condition per participant

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3
0
User Study
Procedure Post Focusing Task
1. Finally, participants were interviewed again
 
about how they experienced the experiment

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1
User Study Result
Focus Accuracy Data Processing
Crop & Stabilized

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2
User Study Result
Focus Measure
= a higher value for a more focused image
J.L. Pech-Pacheco et al.
 
Diatom autofocusing in brightfield microscopy: a comparative studyICPR-2000
46.57
Variance
[
0 1 0
1 −4 1
0 1 0
]
Source Convolved
=Focus Measure
3x3

Laplacian

kernel
(Edge detection)

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3
User Study Result
Focus Measure
46.57
37.61

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4
User Study Result
Focus Measure
46.57
37.61

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5
User Study Result
Focus Accuracy Chart
NR-EVF
R-EVF
NR-EVF
R-EVF
Naked Eye
w/ Visual Aid
0 5 10 15 20 25
Focus Measure (higher is more in-focus)
p > .05 No significant di
ff
erence

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User Study Result
Focus Accuracy White Drawing Mannequin
NR-EVF
R-EVF
NR-EVF
R-EVF
Naked Eye
w/ Visual Aid
25 30 35 40 45 50
ff
erence

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7
User Study Result
Focus Accuracy Blue Drawing Mannequin
NR-EVF
R-EVF
NR-EVF
R-EVF
Naked Eye
w/ Visual Aid
ff
erence
25 30 35 40 45 50

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8
User Study Result
Focus Accuracy Red Drawing Mannequin
NR-EVF
R-EVF
NR-EVF
R-EVF
Naked Eye
w/ Visual Aid
*p < .05 Significant di
ff
erence
25 30 35 40 45 50
*
*

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9
Discussion

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0
Discussion Resolution
Limitation caused
 
by DCRA & light source (Projector)
Suppression of image degradation*
Lattice
*Yahagi et al. 2020. Suppression of floating image degradation
 
using a mechanical vibration of a dihedral corner reflector array.
Combine with image processing
 
e.g., magnification or focus peaking?
R-EVF has lower resolution

than commercial available EVFs

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1
Discussion Focusing Process
In NR-EVF tasks without contact lenses,

I could not see the image clearly.

However, I judged whether in focus or not

by repeating the focus adjustment.“
“
This becomes a problem when using autofocus

as the manual focusing process is omitted in autofocus,
and the user cannot judge whether the image is in focus
during the focusing process.

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2
Discussion Positioning Problem
When using retinal projection,

users are required
 
to place their eye tiny position
Narrow field of view
 
when users see the image
 
from little bit distant e.g., with glasses
Enlarging viewable area?

Suitable camera shape for R-EVF?

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3
Future Work
What is optimal shape

for a camera using the R-EVF?
?

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Retinal Viewfinder:
Preliminary Study of Retinal Projection-Based Electric Viewfinder for Camera Devices
Ippei Suzuki, Yuta Itoh, Yoichi Ochiai
Research and Development Center for Digital Nature, University of Tsukuba, Japan

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Retinal Viewfinder - HCI International 2022 #HCII2022 (Oral presentation by Ippei Suzuki)

Retinal Viewfinder - HCI International 2022 #HCII2022 (Oral presentation by Ippei Suzuki)

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