b.sc. multimedia computingmedia technologies character representation & font technology
TRANSCRIPT
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