Partial Zoom on Small Display
for People Suffering from Presbyopia
Huiyi Fang

Kenji Funahashi

Shinji Mizuno

Yuji Iwahori

Nagoya Institute ofTechnology, Japan30414108@stn.nitech.ac.jp

Nagoya Institute ofTechnology, Japankenji@nitech.ac.jp

Aichi Institute ofTechnology, Japans mizuno@aitech.ac.jp

Chubu University,Japaniwahori@isc.chubu.ac.jp

Figure 1: Partial zoom experiment using tablet PC instead of smartphone: (a) Appearance of an experiment, (b) Original size
screen, (c) The screen that center is zoomed in partially. A gray circle is a touch position pointer, and the point a little above
the pointer is the zooming center.

CCS CONCEPTS• Human-centered computing → Human computer interaction (HCI).

KEYWORDS
Partial display zoom, Presbyopia, Smartphone
ACM Reference Format:
Huiyi Fang, Kenji Funahashi, Shinji Mizuno, and Yuji Iwahori. 2019. PartialZoom on Small Display for People Suffering from Presbyopia. In Proceedings of SIGGRAPH ’19 Posters. ACM, New York, NY, USA, 2 pages.
https://doi.org/10.1145/3306214.3338581

1

difficult to read blurry words (Fig. 3(a)), you can guess and reada sentence includes the blurry words when some other words areclear (Fig. 3(b)). Therefore, we reconsider the zoom-in method forpresbyopic people. For example, the area paid attention is zoomed
in to read clearly, and the magnification rate of the area around it
is gradually reduced to zoom-out rate so that all information is displayed in the small display even though some words are zoomedout. It is expected that you can guess and read also the unzoomedin words like blurred words around the clear zoomed-in words. We
propose a suitable partial zoom-in function that allows you to skima document.

INTRODUCTION

When presbyopic people use digital devices, they often zoom in thedisplay, because it is not in focus when they move it close to face.
We have proposed the automatic display zoom system for presbyopic people [Fang and Funahashi 2018]. However, some of theinformation on the small display has gone out of it after zoomingin (Fig. 2(a) to (b)). It is necessary to scroll it frequently, and abother. On the other hand, a conventional partial zoom means likea magnifying glass is also usually provided (Fig. 2(a) to (c)). The
part around a zoomed area is cut off, and it is necessary to movethe glass frequently too. People sometimes want to skim throughsentences and understand an overview. By the way, although it isPermission to make digital or hard copies of part or all of this work for personal orclassroom use is granted without fee provided that copies are not made or distributedfor profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for third-party components of this work must behonored. For all other uses, contact the owner/author(s).
SIGGRAPH ’19 Posters, July 28 - August 01, 2019, Los Angeles, CA, USA© 2019 Copyright held by the owner/author(s).
ACM ISBN 978-1-4503-6314-3/19/07.
https://doi.org/10.1145/3306214.3338581

Figure 2: Conventional zoom examples

Figure 3: Example to guess a meaning of a sentence withblurred words from clear print words

SIGGRAPH ’19 Posters, July 28 - August 01, 2019, Los Angeles, CA, USA2

REQUIREMENT OF PARTIAL ZOOMThe requirement of our novel partial zoom is that all informationof a document is displayed even though some of them are zoomedout. Fig. 4 shows the relation between the position (one dimension)
on a display and the magnification rate there. The width of the display is w on a horizontal axis x, the center of the area paid attention is a, and the magnification rate is represented as the verticalaxis y. The normal magnification that is unzoom, the usual zoom,
and magnifying glass zoom are shown as Fig. 4(a)-(c) respectively.
Each area enclosed by the magnification rate line and x axis forthe width should be same. Fig. 4(d) shows the outline of our zoom.
The magnification rate changes continuously, the value at the area
paid attention is larger than 1.0, and it is reduced gradually to thevalue smaller than 1.0. Of course there is no lack of data.

3

H. Fang et al.

Figure 5: Partial zoom ofa grid image

Figure 6: Partial zoom ofa map image

PARTIAL ZOOM OF TEXT AND IMAGE

Here we want to apply our proposed zoom mentioned above to an
actual document contains text and image i.e. a PDF file and a webpage. However it difficult to decide the two-dimensional magnification curve, we configure a pilot system empirically to evaluate
our method. First, we consider text data, it is not necessary thatthe magnification rate changes continuously exactly, because thedeformed letter is not appropriate to read. In order to zoom eachletter in the line read and paid attention, magnification rate R(x)for the letter position x is defined as follows,(a ≤ x ≤ A1 + a)rR(x) =(1))
r − 1.0(
r −x − (a + A1 )A2(A1 + a < x ≤ A1 + A2 + a)
for x ≥ a which is the center letter position paid attention, where
A1 is the number of letters required to understand the word itself meaning, and the letters are zoomed in with the fixed maximum rate r. Also, A2 is the number of additional letters required
to guess other words forward of the word paid attention, it means
to guess the sentence outline. In our pilot system, parameters aredefined as A1 = 4, A1 +A2 = 14 based on the references [Rayner1975] [McConkie and Rayner 1975]. And the maximum rate is defined as r = 1.5 empirically. The backward area letters are notmentioned in the research, we apply the equation symmetricallyFigure 7: Partial zoom of an integrated document
about the center position. Outside of the zoomed-in area that magnification rate is more than and equal to 1.0, the same rate is applied for the letters there to keep the total length of the line. Although the baseline as the vertical position of each line is kept tokeep the total layout, upper and lower lines are also zoomed in by asame way with the rate r = 1.3 not to lose sight of the line while
swiping the screen. Fig. 1 shows the original size text document
and partial zoomed one. Next, we consider image data. Although
it is desirable that the aspect ratio at any point is 1.0 locally, square
image do not partial-zoomed in to the square. So we apply the empirical one-dimensional magnification curve to both vertical andhorizontal direction on an image (Fig. 5). Fig. 6 shows the original
size image data and partial zoomed one. Fig. 7 is an example tozoom in the border of an integrated text and image document. In
addition, when the area indicated to zoom-in is on the far side, it
is handled exceptionally.

4 RESULT AND CONCLUSION
We implement our idea on a tablet PC to develop an experimental system, and presbyopic people try to use it to check how it
works (Fig. 1). Since a tablet screen is not too small to zoom in,the display area is limited to smartphone size. The area a subject
wants to see more detail is specified by touching on a screen. The
center of a screen is zoomed in partially and the surroundings arezoomed out (Fig. 1(c)) from the original screen (Fig. 1(b)) when asubject touches the center. The subjects said that it was easier toread than the usual zoom and the magnifying glass zoom. In thefuture, the area paid attention should be pointed by an eye tracker.
We should also consider asymmetric zoom, because the right areaof the words paid attention is more important than the left one.

REFERENCES

Figure 4: The relation between the position on the display
and the magnification for each zoom method

Huiyi Fang and Kenji Funahashi. 2018. Automatic Display Zoom for People Suffering from Presbyopia. In ACM SIGGRAPH 2018 Posters (SIGGRAPH ’18). 2.
https://doi.org/10.1145/3230744.3230754
George McConkie and Keith Rayner. 1975. The span of the effective stimulus during a fixation in reading. Perception & Psychophysics 17 (11 1975), 578–586.
https://doi.org/10.3758/BF03203972
Keith Rayner. 1975. The perceptual span and peripheral cues in reading. Cognitive
Psychology 7, 1 (1975), 65 – 81. https://doi.org/10.1016/0010-0285(75)90005-5