LEGIBILITY OF AN ELECTRONIC BOOK

FOR PARTIALLY-SIGHTED PEOPLE

Dominique BURGER
Dominique.Burger@snv.jussieu.fr
INSERM U483

Pauline VIGOUREUX

Université Pierre et Marie Curie
9, quai Saint Bernard
75252 Paris Cedex 05

Keywords. Electronic book, visual handicap, partially-sighted persons.

Abstract. This paper investigates the usability of an electronic book by partially-sighted persons. It examines the needs of these users, from which it recommends some improvements aiming at a better accessibility of this new type of reading device.

INTRODUCTION

One of the major difficulty encountered by visually handicapped people is to access written information. Partially-sighted people have to use specialised computer equipments (magnifying software, reading machines, electronic enlargement system, …) which are often expensive, heavy and cumbersome [1]. As electronic books, also called e-books, have the flexibility for adapting the presentation of contents to the preferences of readers, they could make them accessible to partially-sighted readers directly without any additional equipment. This is the point we investigated in a study aimed at assessing the usability of one electronic book by partially-sighted people. This device, called Cybook, is manufactured by Cytale. It was chosen for quality of its display screen. This first study gave some hints concerning the needs of people with low-vision using this type of devices. It also suggested some recommendations for improving the readability of e- books.

HARDWARE

scheme of e-bookAn e-book includes a LCD touch screen. The size of the screen varies according to the model, from an A4 format down to the A5. The weight is between 400g and 2 kg. An e-book can store digital files representing up to several tens of books. It is equipped with a modem making it possible to connect to an Internet site from where to download digital books [2].

 



The Cytale electronic book is provided with a 21 cm by 16 cm (10.4 inches) screen. It weights around 800 g. Simple commands make it possible to turn pages, to choose another book, to access a dictionary, … [2 ]. Its memory contains up to 150000 pages, i.e. approximately 30 books. This memory may be extended by an additional PCMCIA card making possible to store several hundreds of books. The design paid a lot of attention to legibility so that the user can modify the size of fonts while preserving the coherence between text and images. The Cybook has an autonomy of five hours approximately, depending on the selected luminosity. The Cytale e-book offers many functions accessible on a menu activated by a physical button situated on the side (2) and controlled by touch on the screen:

A button controls the luminosity (3). Two buttons make it possible to go to the next page (4) or the preceding one (5).

EVALUATION METHOD

The evaluation took place during individual sessions with partially-sighted people. After a presentation and brief demonstration of the Cybook, the user was invited to carry out two types of tasks depending on his/her handicap. If possible the e-book was used autonomously, the user following the instructions given by the experimenter. In some cases nevertheless, the experimenter carried out the manipulation of the device showing the displayed pages to the subjects. All users were invited to express themselves freely on the use of the e-book and to propose new functions. Results were collected by means of half-directed discussions and direct observation. Additionally, alternative lay-out could be presented on a computer screen to enlarge the possible choice concerning font sizes and chromatic contrasts. This was done by means of HTML 4.0 cascading style sheets and Internet Explorer). SUBJECTS The study was carried out with nine partially-sighted users, met in three different places:

Acuity
Number of users
1/10th - 1/20th
5
1/20th - 1/40th
2
+ of 1/40th
2

Table 1 : Table showing users according to their visual acuity.

Table 1 shows the visual acuity of the subjects we divided into two groups:

Subjects presented different types of handicap which involved a great diversity in reading capacities, assistive tools and needed assistance.

RESULTS

Observation results were classified according to the main features of the Cybook :

Suggestions from the users are also presented.

Font size

5 out of 9 subjects could read the text choosing the most suitable size and font. Four subjects could not find any appropriate size proposed by the Cybook. Nevertheless, they could read the largest size on the computer, i.e. 50.

Luminosity

Big discrepancies were observed in the choice of luminosity as shown by Figure 2.

scheme of choise of luminosity

Figure 2: Users' choice on the scale of luminosity

Contrast

Seven subjects appeared satisfied with the standard colour : white background - black foreground. Two subject would have been authorised to choose different colour features.

Homepage

As the font size of the homepage could not be modified. A great number of subjects had difficulties to read titles of books and the main menus on this page.

Keyboard

The size of the screen keyboard was too small for several subjects.

Suggestions from users

Most of the suggestions recorder are mentioned even if they have only an indicative value.

Recommendations

The results of this study carried out on the Cybook suggested some recommendations to improve the accessibility of e-books for visually-sighted people.

Display

Navigation

CONCLUSION

All subjects expressed a keen interest for the potential that e-books represent; The legibility of the Cybook was considered as encouraging. The main positive aspects that were evoked were:

ACKNOWLEDGEMENT

The authors wish to express their gratitude to Olivier Pujol, Cytale, Professor Henry Hamart and Marie Michel-Deschamps, "Centre Hospitalier National d'Ophthalmology des Quinze-Vingts", Mr Hamelot and his team, Valentine Haüy Association, who have contributed to this study. They thank finally all the users who took part in the study, for their patience, their desire to help progress in this technology and their kindness.

REFERENCES

1. Safran, A.B. (1995) Le déficit visuel: De la Neurophysiologie à la pratique de rééducation. Masson, Paris.

2. Cytale web site: http://www.cytale.com

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