B.Sc. Multimedia ComputingMedia Technologies

Character Representation & Font Technology

Agenda Character Sets

Standards (ASCII) Unicode and ISO 10646

Fonts Accessing Fonts Classification and Choice Terminology Font Technology

Text – Nature and Aesthetic Visual representation of a language Graphical symbols with visual aesthetics Characteristics

Shape Spacing Structure Layout

Characters and Representation

The quick brown foxjumps over the lazy dog

(courier)

The quick brown fox

jumps over the lazy dog

(Garamond)

Characters and Representation

‘Content is part of the text that carries its meaning or semantics, while the appearance is a surface attribute that may affect how easy it is to read, or how pleasant it is to look at.’

Chapman & Chapman (2004)

Abstract character - content Graphical representation - appearance

Abstract Characters

Grouped into alphabets Alphabets describe written form of a given language Upper and lower case require different symbols

A, B , C, …Z, and a, b, c, …z Punctuation marks :;,. ! Numerals and operator symbols 0, 1, 2, 3… + - x ^ =

Digital Representation Set of abstract characters for a given language is

called the ‘Character Repertoire’. Each maps to a distinct ‘code point’ .

Map each abstract character of the given language to a code stored in a computer.

Representation of the English alphabet would require 2 * 26 = 52 codes, and 0..9 for numerals, and punctuation marks etc.

An 8-bit computer gives 28= 256 possible codes. OK for English. Other languages would require more codes.

Representation

27 26 25 24 23 22 21 20

1 1 1 1 1 1 1 1128 64 32 16 8 4 2 1

128 + 64 + 32 + 16 + 8 + 4 + 2 + 1Totals 256 possible codes (0 - 255)

Digital Representation - ASCII

American Standard Code for Information Interchange Dominant since the 1970s Uses 7 bits to store each code value, giving 128 code

points. ASCII repertoire only comprises 95 characters code Values 0 to 31, and 127 mapped to control

characters, form-feed, carriage return, and delete etc.

Text Encoding Standards 256 code points not sufficient for many languages 32 - bit encoding scheme prescribed by ISO 10646

gives structured access to full range of languages and sub-encodings e.g. ASCII

Unicode 16–bit character set also developed in parallel providing code values for all ‘major’ languages.

ISO 10646 and Unicode standardized in early 1990s See Chapman & Chapman Ch.10 p319-p324

Font Technology

Each stored character value mapped to a visual display called a glyph.

Glyphs arranged in collections called fonts Concept of fonts as collection of glyphs visually

related and design to work together dates back to pre-digital era.

Some font designs originate from fifteenth century.

Accessing Fonts Font shape (glyph) visual representation of encoded

text. Fonts only available on local system – can’t

guarantee audience will have fonts on their local system

‘System’ fonts may vary across platforms e.g. Windows and Mac

Need to embed font shapes with text thereby delivering fonts to audience

Embedded fonts will increase file sizes

Font Classification and Choice Thousands of fonts available!

Major distinction is between monospace and proportional

monospace - each letter occupies the same amount of horizontal space - has typewriter look - this is courier - designed by IBM

Proportional - Each letter occupies an amount of horizontal space proportional to the width of the glyph. Has the appearance of book text.

Fonts: Sans Serif

Sans Serif fonts lack the tiny strokes known as serifs and tend to have a plain appearance

HComic Sans, for example

Font Classification and Choice Specific modification of font style such as

Italic or bold will require further font set to achieve this effect.

Font Terminology Finest grained unit of measurement is the point (pt). Digital typography 1point = 1/72 of an inch ~=

0.36mm. The ‘point’ is unit used to describe dimensions of

small objects such as typeset characters. Larger quantities such as distance between lines is

measured in Picas, I Pica = 12pt = 1/6 in =~4.23 mm. A font’s size is quoted in points, ‘12 point Times

Roman’ or ‘10pt Arial’.

Font Terminology

x-height

cap height

baseline descender

ascender

body size

Font adjustments: Kerning

Kerning – when spacing between individual font characters requires adjustment through layout effects, or by virtue of the fonts style.

The Title

The Title

space requires ‘kerning’

Digital Font Technology Glyphs stored as bitmaps or vector graphics (bitmap

fonts & outline fonts) respectively. Bitmap fonts lose resolution when scaled Fonts are predominately of the outline variety Adobe Type 1 (Postscript) and Truetype Newly developed format Opentype, based on

Unicode standard, provides for better cross-platform font support.

Font Examples

Using Fonts Fonts libraries loaded at system start Too many installed fonts will degrade system

performance Where possible create graphical representation of

desired fonts - e.g for webpage deployment etc. Embed fonts when deploying media such as Flash or

Director Artwork normally supplied with fonts for further

preparing or presentation.

References Digital Multimedia Chapman & Chapman 2004