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Character-related factors

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Typeface

The following factors are of particular importance for the selection of suitable typefaces for people with visual impairments:1

Recognizability

Recognizability is understood as the property of individual characters that enables them to be identified and distinguished from others2 .

The letter G is shown in Fraktur. The letter G is shown as handwriting font. The letter G is shown in a Sans Serif.

In order for letters to be recognized, they must first be learned. Their form follows established conventions in each case. The fact that these three letters designate the same consonant is not formally comprehensible and can only be identified by knowledgeable readers.

Discernibility

The discernibility of individual letter forms facilitates the quick grasp of their meaning.

Futura

Unit

While Geometric Sans-Serifs, which follow a geometric form principle, often have very similar letter forms (top), characters of Humanist Sans-Serifs, which follow a dynamic form principle, differ more clearly from each other (bottom).

Gill

Arial

Neue Frutiger 1450

Confusable character forms can also be found at 1, I and l .

Aperture

The size of the apertures of character shapes strengthens their distinguishability in poor print quality, blurred vision, halation, or poor lighting conditions, which is especially evident with the lower-case letters a, c, e, o, or s.

Permafrost
Permafrost

The blur simulation shows that characters with small apertures, typical to the static form principle of the Neo-Grotesque (top: Arial) are less distinguishable from each other than characters with large apertures, typical to the dynamic form principle of the Humanist Sans-Serif, (bottom: Neue Frutiger 1450).

Stroke contrast

High contrasts between stem and hairline, as exhibited in particular by Didone typefaces (Modern Face), lead to fine lines breaking away or no longer being perceived at small sizes, in the case of halation, poor print quality, weak background contrast or low screen resolution. Garalde (Old Style) and sans serif typefaces generally have lower stroke contrasts than other typefaces and are therefore more suitable for readers with impaired vision.

A
A

Stroke contrasts vary greatly depending on the form principle of each group as can be seen in this simplified illustration. While Didone typefaces often have very fine hairlines, Garalde typefaces have stronger hairlines, also the horizontal curves as in h, m, n and u as well as in b, d, p and q are much thicker. The Transitional is an intermediate form between the two. The Sans Serif (Lineale) usually has a lower contrast between stems and hairlines. However, the individual typefaces within the classification group are subject to a wide variety of forms, which is why classification systems of typefaces offer only a rough orientation.

Typeface

geometric
form principle
static
form principle
dynamic
form principle
Sans Serif typefaces
(Grotesk)
Geometric Sans Serif
(e.g. Futura)
Neo-Grotesque
(e.g. Helvetica)
Humanist Sans Serif
(e.g. Unit)
Serif typefaces
(Antiqua)
Slab Serif
(e.g. Lubalin Graph)
Didone
(e.g. Bodoni)
Garalde
(e.g. Garamond)
The sequence of letters I l a q e g is shown in typefaces without serifs in the top row and typefaces with serifs in the bottom row, each in three different typefaces that follow the geometric, static, respectively dynamic form principle.

This simplified overview of the different form principles3 of typefaces with and without serifs shows that sans-serifs, which follow the dynamic form principle, have better distinguishable and more open letter forms with lower stroke contrast than other typefaces. Typefaces of this form principle are especially recommended for signage text, due to situational influences on the reading conditions placing a high demand on legibility.4

Since people with visual impairments generally have higher legibility requirements, these readers favour Humanist Sans-Serifs for all text types.

The typeface samples shown below are examples of typefaces of this form principle.

Typefaces delivered with operating systems or software (not separately chargeable)

The illustration shows a sample of the font Calibri Regular.
Calibri Regular
The illustration shows a sample of the font Lucida Sans Regular.
Lucida Sans/Grande Regular
The illustration shows a sample of the font Verdana Regular.
Verdana Regular

Open source typefaces (free of charge according to the terms of use)

The illustration shows a sample of the font Noto Sans Regular.
Noto Sans Regular, available from Google Fonts.
The illustration shows a sample of the font Open Sans Regular.
Open Sans Regular, available from Google Fonts
The illustration shows a sample of the font Source Sans Pro Regular.
Source Sans Pro Regular, available from Google Fonts
The illustration shows a sample of the font Fira Sans Regular.
Fira Sans Regular, available from Google Fonts

Licensed typefaces (fee required)

The illustration shows a sample of the font Frutiger 55 Roman.
Frutiger 55 Roman, Distribution: MyFonts
The illustration shows a sample of the font Neue Frutiger 1450 Regular.
Neue Frutiger 1450 Regular, Distribution: MyFonts
The illustration shows a sample of the font FF Meta Book.
FF Meta Book, Distribution: MyFonts
The illustration shows a sample of the font FF Milo Text.
FF Milo Text, Distribution: MyFonts
The illustration shows a sample of the font Myriad Regular.
Myriad Regular, Distribution: Adobe
The illustration shows a sample of the font TheSans Regular.
TheSans Regular, Distribution: LucasFonts
The illustration shows a sample of the font Wayfinding Sans Regular.
Wayfinding Sans Regular, Distribution: FDI

Summarized Recommendations
Typeface

Footnotes

  1. ↑ DIN 1450
    Lettering – Legibility
    April 2013 edition

    Jan Filek
    Read/ability – Typografie und Lesbarkeit
    Niggli 2013

    Ralf Herrmann
    TypoJournal 2, 2010
    www.typografie.info
  2. ↑ DIN 1450
    Lettering – Legibility
    April 2013 edition
  3. ↑ Indra Kupferschmid
    Buchstaben kommen selten allein
    Niggli 2001

    Hans Peter Willberg
    Wegweiser Schrift
    Verlag Hermann Schmidt Mainz 2001
  4. ↑ DIN 1450
    Schriften – Leserlichkeit
    April 2013 edition

    Ralf Herrmann
    TypoJournal 2, 2010
    www.typografie.info

    Florian Adler, Sven Neumann
    Leserlichkeit von Schrift im Öffentlichen Raum
    in: J. Eckert, C. Fischer, I. Pfeiffer, P. Schäfer, A. Uebele u. a. (Hg.)
    Schrift und Identität, Niggli 2013