Open Type Versus True Type Fonts Computer Science Essay

Brief HistoryTrueType ( TT ) , PostScriptA® Type 1 ( Type 1 ) and Open TypeA® are all multi-platform lineation fount criterions for which the proficient specifications are openly available. “ Multi-platform ” means that both font types are useable on multiple kinds of computing machine systems. “ Outline fount ” means that they describe missive forms ( “ glyphs ” ) by agencies of points, which in bend define lines and curves. This representation is resolution independent, intending that lineations, by their very nature, can be scaled to reasonably much any arbitrary size. Depending on the peculiar plan being used and the operating system it ‘s run under, there may be upper and lower bounds to the size the fount can be scaled to, but few users will of all time meet these bounds.An outline fount must be represented by the points of the end product device, whether it ‘s screen pels or the points of a optical maser, ink-jet or wire-pin pressman. The procedure of change overing the lineation to a form of points on the grid of the device is called “ rasterization.When there are n’t adequate points doing up the glyph ( such as at little sizes or low declarations ) ,there can be incompatibilities in the representation of certain missive characteristics, at a individual size, due to different rounding based on how the lineation happens to sit on the grid. A common signifier of this is that the breadths of the missive stems can change when they should n’t. Worse, cardinal characteristics of the glyphs can vanish at little sizes.However, Type 1, TrueType and Open Type founts all have a agency of covering with these incompatibilities, called “ hinting.” This consists of extra information encoded in the fount to assist forestall these jobs.PostScript and the Type fount format predate TrueType by about six old ages ( with Open Type beinga much later merger of the two formats ) . First, we had many different formats for digital founts, none of which were standardized. Then Apple adopted the AdobeA® PostScript page description linguistic communication ( PDL ) for its Apple LaserWriter pressman in 1985. It is, combined with the debut of PageMakerA® , the first desktop publication package, sparked a revolution inpage layout engineering.Soon the PostScript linguistic communication was adopted for usage in higher-end image puting devices, and became the native operating manner and linguistic communication of many artworks plans every bit good. The bid construction of the PostScript linguistic communication was publically available, so it was possible for person to construct a PostScript translator to vie with Adobe ‘s rasterizing package. Butit would n’t be able to construe the intimations in Type 1 founts. This was because the PostScript font specification for Type 1 founts, which included hinting, was non publically available. Adobe had merely released the specifications for Type 1 founts. Type 1 founts were a more general format, but Type 3 was smaller, faster, and had a native hinting construction ( of which see more below ) .It quickly became obvious to the major system package Godheads ( Apple, Microsoft, and subsequently IBM ) that it was of import to hold scaleable font engineering supported at the degree of the operating system itself. This would let much better screen show, compared to pre-made electronic images which would merely look good at a few sizes, and would be jagged at all others. So in the late eightiess, Apple developed its ain scaleable fount engineering, First code-named Royal,and subsequently introduced as TrueType.Apple traded the engineering to Microsoft in exchange for the latter ‘s TrueImage PostScript ringer engineering ( which was buggy at the clip, and ne’er used by Apple, although it has surfaced in assorted ulterior embodiments ) . The TrueType specifications were made public, and TrueType was built into the following versions of the Mac and WindowsA® runing systems, released in 1991.Adobe ‘s response started with the release of the long-protected specifications for the PostScript Type 1 fount format in March 1990. This was followed by debut of Adobe Type ManagerA® ( ATMA® ) package in mid-1990. ATM scales PostScript Type 1 founts for screen show, and for imaging on non- PostScript pressmans.In early 1991, TrueType for the Mac became available, followed by the Windows 3.1 execution ( the Windows scaler was and remains somewhat more Accurate / efficient than the Mac version, though it ‘s nil a normal user is likely to notice ) . Now, with either TrueType or ATM, Mac users ( and subsequently Windows and OS/2 users ) could really see on-screen atany size what the fount end product would look like.The first difference between TrueType and PostScript founts is their usage of different kinds of mathematics to depict their curves. Open Type founts can hold either sort of lineations, with their several advantages and disadvantages.Some articles have said that TrueType founts require more points than PostScript, or that they take longer to rasterize because the math is more complicated. In fact, the math is simpler ( quadratics are simpler than cubics ) . Although a few forms take fewer points in TrueType than in PostScript ( a perfect circle takes twelve points in PostScript vs. eight in TrueType ) , in pattern the forms in real-world founts all tend to take more points in TrueType, it ‘s true that most founts will stop up utilizing more points in TrueType, even if the sort of mathematics used to depict the curves is simpler.The primary advantage of TrueType over Type 1 founts is the fact that TrueType has the potency for better hinting. Mind you, PostScript Type 1 intimations manage a batch: perpendicular and horizontal characteristics, wave-offs, root catchs, equal counters, and shallow curves ( “ flex ” ) . Several of these can hold a threshold pel size at which they activate.However, TrueType intimations can make all that PostScript can, and about anything else, as defined by the really flexible instructions of the TrueType linguistic communication. This includes commanding diagonals, and traveling specified points on the glyph lineations at specific arbitrary sizes to better discernability. This ability to travel points at a specific point size allows font production staff to hand-tune the electronic image form produced by the out-line at any specified size. Or at least it used to ; more recent divergencies in TrueType rasterizing between different participants ( including Apple and Microsoft ) make this a little more unsure.This difference in suggesting doctrine is truly diagnostic of a larger philosophical difference. PostScript uses “ dumber ” founts and a “ smarter ” translator, while TrueType utilizations comparatively smarter founts and a dumber translator. This means that PostScript intimations tell the rasterizer what features ought to be controlled, and the rasterizer interprets these utilizing its ain “ intelligence ” to make up one’s mind how to make it. iˆ•ere-fore, when person upgrades their PostScript translator, the rasterization can be improved.Technical DifferencesContrariwise, TrueType puts all the suggesting information into the fount to command precisely how it will look when rasterized. Some TT aficionados prefer to name TrueType intimations “ instructions, ” partially in mention to the full-featured nature of the TrueType scheduling linguistic communication, but besides to clear up the function of this information. As Jelle Bosma of Agfa Mono- type says, “ I do n’t hintA at what I want to happen-I tellA the fount what to make. ”