B.Sc. Multimedia ComputingMedia Technologies Character Representation & Font Technology

Agenda Character Sets Standards (ASCII) Unicode and ISO 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 fox jumps over the lazy dog (courier) T he 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 2 8 = 256 possible codes. OK for English. Other languages would require more codes.

Representation Totals 256 possible codes ( )

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 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 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 H Comic 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 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