Harsha Wijayawardhana University of Colombo School of Computing (UCSC)

 Typography is the art of arranging type, type design and modifying type glyphs  Arrangement of type involves the following:  Typefaces  Point sizes  Line length  Leading (line spacing)  Adjusting space between group of letters (Tracking)  Adjusting space between pair of letters (Kerning)

 Typeface – a typeface is a set of one or more fonts, in one or more font sizes. The distinction between font and typeface is that a font designates a specific member of a type family such as roman, boldface, or italic type, while typeface designates a consistent visual appearance or style which can be a "family" or related set of fonts

Typefaces and fonts are measured in points Point has been defined differently in different period and in digital era, the most popular is the Desktop Publishing point of 1 ⁄ 72 in ( in/0.35 mm). It is now accepted that 72 point is an inch  There are two types of Typefaces: Serif and San Serif

 EM Unit measurement of typeface of a font.  Typeface of 16 point of font is 1 EM  Fontlab measures in UPM or Unit per EM  This is the way how the calculations are done and it is brought to FontLab  These calculations are performed for Type 1 PS fonts, which is 1000 points and TTF 1024 and 2048 (Microsoft)

 Assuming my EM square 260 mm  Caps = 200 mm  Ascender = 200 mm  x-height = 140 mm  Descender = -60  Caps 200/260 * 1000 = 769  Ascender 200/260 * 1000 = 538  x-height 140/260 * 1000 = 769  Descender -60/260 * 1000 = -231