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[ I ripped this right out of the manual I wrote for Sfware. If you have comments, improvements, suggestions, please tell me... ]
[ed: this is an 'off-the-cuff' definition, feel free to clarify it for me ;-) ]
On low-resolution bitmap devices (where ragged, ugly characters are the norm) which support more than two colors, it is possible to provide the appearance of higher resolution with anti-aliasing. Anti-aliasing uses shaded pixels around the edges of the bitmap to give the appearance of partial-pixels which improves the apparent resolution.
The baseline is an imaginary line upon which each character rests. Characters that appear next to each other are (usually) lined up so that their baselines are on the same level. Some characters extend below the baseline (``g'' and ``j'', for example) but most rest on it.
A bitmap is an array of dots. If you imagine a sheet of graph paper with some squares colored in, a bitmap is a compact way of representing to the computer which squares are colored and which are not.
In a bitmapped font, every character is represented as a pattern of dots in a bitmap. The dots are so small (300 or more dots-per-inch, usually) that they are indistinguishable on the printed page.
(1) The smallest component of written language that has semantic value. Character refers to the abstract idea, rather than a specific shape (see also glyph), though in code tables some form of visual representation is essential for the reader's understanding. (2) The basic unit of encoding for the Unicode character encoding, 16 bits of information. (3) Synonym for ``code element''. (4) The English name for the ideographic written elements of Chinese origin.
Downloading is the process of transferring information from one device to another. This transferral is called downloading when the transfer flows from a device of (relatively) more power to one of (relatively) less power. Sending new fonts to your printer so that it ``learns'' how to print characters in that font is called downloading.
A particular collection of characters of a typeface with unique parameters in the 'Variation vector', a particular instance of values for orientation, size, posture, weight, etc., values. The word font or fount is derived from the word foundry, where, originally, type was cast. It has come to mean the vehicle which holds the typeface character collection. A font can be metal, photographic film, or electronic media (cartridge, tape, disk).
(1) The actual shape (bit pattern, outline) of a character image. For example, an italic 'a' and a roman 'a' are two different glyphs representing the same underlying character. In this strict sense, any two images which differ in shape constitute different glyphs. In this usage, ``glyph'' is a synonym for ``character image'', or simply ``image''. (2) A kind of idealized surface form derived from some combination of underlying characters in some specific context, rather than an actual character image. In this broad usage, two images would constitute the same glyph whenever they have essentially the same topology (as in oblique 'a' and roman 'a'), but different glyphs when one is written with a hooked top and the other without (the way one prints an 'a' by hand). In this usage, ``glyph'' is a synonym for ``glyph type,'' where glyph is defined as in sense 1.
When a character is described in outline format the outline has unlimited resolution. If you make it ten times as big, it is just as accurate as if it were ten times as small.
However, to be of use, we must transfer the character outline to a sheet of paper through a device called a raster image processor (RIP). The RIP builds the image of the character out of lots of little squares called picture elements (pixels).
The problem is, a pixel has physical size and can be printed only as either black or white. Look at a sheet of graph paper. Rows and columns of little squares (think: pixels). Draw a large `O' in the middle of the graph paper. Darken in all the squares touched by the O. Do the darkened squares form a letter that looks like the O you drew? This is the problem with low resolution (300 dpi). Which pixels do you turn on and which do you leave off to most accurately reproduce the character?
All methods of hinting strive to fit (map) the outline of a character onto the pixel grid and produce the most pleasing/recognizable character no matter how coarse the grid is.
(noun): That portion of a letter which extends beyond its width, that is, the letter shapes that overhang - the projection of a character beyond its sidebearings.
(verb): To adjust the intercharacter spacing in character groups (words) to improve their appearance. Some letter combinations (``AV'' and ``To'', for example) appear farther apart than others because of the shapes of the individual letters.
Many sophisticated word processors move these letter combinations closer together automatically.
See 'scalable font'
The (more or less) original point system (Didot) did have exactly 72 points to the inch. The catch is that it was the French imperial inch, somewhat longer than the English inch, and it went away in the French revolution. What most people now think of as points were established by the United States Typefounders Association in 1886. This measure was a matter of convenience for the members of the Association, who didn't want to retool any more than they had to, so it had no relationship to the inch. By that date, people realized that the inch was an archaic measure anyway; the point was set to be 1/12 of a pica, and an 83-pica distance was made equal to 35 centimeters. (Talk about arbitrary!)
Thus the measure of 72.27/in. is just an approximation. Of course, when PostScript was being written, it was necessary to fit into an inch-measured world. For the sake of simplicity PostScript defined a point as exactly 1/72". With the prevalance of DTP, the simplified point has replaced the older American point in many uses. Personally, I don't see that it matters one way or the other; all that counts is that there's a commonly-understood unit of measurement that allows you to get the size you think you want. That is, after all, the point ;)
A scalable font, unlike a bitmapped font, is defined mathematically and can be rendered at any requested size (within reason).
A softfont is a bitmapped or scalable description of a typeface or font. They can be downloaded to your printer and used just like any other printer font. Unlike built-in and cartridge fonts, softfonts use memory inside your printer. Downloading a lot of softfonts may reduce the printers ability to construct complex pages.
The symbol set of a font describes the relative positions of individual characters within the font. Since there can only be 256 characters in most fonts, and there are well over 256 different characters used in professional document preparation, there needs to be some way to map characters into positions within the font. The symbol set serves this purpose. It identifies the ``map'' used to position characters within the font.
The features by which a character's design is recognized, hence the word face. Within the Latin language group of graphic shapes are the following forms: Uncial, Blackletter, Serif, Sans Serif, Scripts, and Decorative. Each form characterizes one or more designs. Example: Serif form contains four designs called Old Style, Transitional, Modern, and Slab Serif designs. The typeface called Bodoni is a Modern design, while Times Roman is a Transitional design.