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TrueType vs. Type 1
Part I
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“GX is not specific to either TrueType or PostScript Type 1; GX fonts are an extension of either font specification.”
“GX fonts allow extended character sets beyond the usual 256 allowed by standard TrueType and PostScript type 1 fonts.”
“The biggest software vendors have released any applications which are GX-savvy.”
“The Unicode character encoding is directly supported by Windows NT. It is not currently supported at the system level by any other major operating system.”
“Microsoft and Adobe licensed the TrueType and PostScript font technologies to each other.”
“The OpenType format will support all the most advanced features of existing TrueType and PostScript formats.”
“OpenType was created by the leading maker of business software (Microsoft) and the leading creator of graphics software (Adobe). If even only these two companies’ applications support OpenType to start with, that would be much further than GX got with mainstream applications.”
“OpenType may be a savior in the font wars, but first it will have to be supported at the operating system level, and applications will need to be re-engineered to take advantage of its more whizzy features.” |
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Multiple Masters
The Multiple Master (MM) format is an extension of the Adobe Type 1 PostScript font format. Essentially, it allows two design variations to be encoded as opposing ends of a single design axis. Afterwards, any in-between state may be generated by the user on need. Thus, a MM font could have a “weight” axis which has an ultra-light master and an extra-black master, allowing any conceivable variation in between. And this is only one possibility; almost any two design extremes could theoretically be put on a multiple master, as long as their Bézier control points can be matched up to allow interpolation.
 Multiple axes are also possible, but each additional axis doubles the number of master fonts that must be created, because each possible extreme must be designed separately. Imagine a dimensional space, with each corner requiring a master. Thus a three-axis MM (a cube) must have eight master fonts; a four-axis font (the theoretical maximum) would need sixteen master fonts, which is one reason nobody has released one yet.
The primary uses to which MM technology have been put are: weight (light to bold); width (condensed to extended); and optical size (text to display). A few MM fonts experiment with other forms, such as the existence or type of serifs. All of these adjustments can be done by cruder means, by creating separate fonts, or even just ignored; but MMs allow typographically-aware users to create the precise, desired typeface in a more refined fashion.
As of this writing, fewer than 36 MM fonts have been released by major font vendors—and more than half by Adobe. Using Multiple Masters also requires that the user have Adobe Type Manager, but this is a near-necessity for PostScript fonts anyway.
There are a few older devices with implementations of PostScript level 1 that can’t handle MM fonts, notably Apple’s Personal LaserWriter NT, the HP LaserJet IIID, the PostScript cartridge for the HP LaserJet IIP, the TI microLaser PostScript series, and some older PostScript clones.
A more common problem with MM technology is that it can be inconvenient to access additional MM variants. At present, much of the time, the user must use ATM (or a “Font Creator” utility with Mac ATM prior to 4.0) to instantiate each additional font variant in order to make it available to the system. There are a few exceptions: Microsoft Word 6 & 7 support direct creation of MM instances on the fly by typing the exact name of the instance (easy, but hardly obvious). PageMaker 6 also has integrated support for creating and using MM instances, as does QuarkXPress 3.3x, via an included extension. But because this is less convenient, and many users are unfamiliar with MM technology, it often makes more economic and marketing sense to release a font set as multiple Type 1 variants, even if it was designed using multiple master-style interpolation. An example of this trend is Jonathan Hoefler’s reworking of Didot.
If there were better system-wide and/or application-level support for MM fonts, they might be more popular. CompuServe DTP Forum Sysop and typography writer Kathleen Tinkel says, “if MM fonts were to become easier to use, I think we’d see another two dozen fonts very quickly.”
QuickDraw GX & GX Fonts
Another attempt to enhance these typographic niceties (and then some) is Apple’s QuickDraw GX, and GX fonts. GX is not specific to either TrueType or PostScript Type 1; GX fonts are an extension of either font specification, although there are some additional features possible in TrueType GX fonts.
TrueType GX fonts have essentially the same capability as Multiple Masters vis-à-vis design axes. However, they also have greater flexibility in the use of these axes. Although master fonts can be put at each corner of the design space, each axis has a minimum requirement of one new outline at the end of each axis; this means that instead of doubling the number of masters, each axis could simply add one instead. Thus, for example, it would be possible to have an eight-axis GX font that only had nine master designs, instead of the 256 it would take in Multiple Master technology. Of course, designers taking advantage of this feature must be careful, because the corners of the design space must be created by vector addition, which has the potential to create unexpected problems in the corners of the design space.
Of equal or greater interest to the average user is the potential inherent in the GX Line Layout Manager. This bit of system software can interpret and manage additional information encoded in a font to do all sorts of nifty things, such as automatic intelligent ligature substitution, or optically aligning the edges of text based on the actual shapes of the letterforms rather than the outside of the character bounding box.
GX fonts also allow extended character sets beyond the usual 256 allowed by standard TrueType and PostScript type 1 fonts. These could be alternate letterforms, or those characters usually included in “expert sets,” or foreign languages, or whatever the designer desires. The difference between this and the currently available “expert sets” and “alternates” is that the user simply chooses between stylistic variations encoded in the single font, which could include specific languages, old style figures, ligatures or swashes. Further, either regular or special characters can also substitute themselves intelligently based on adjacent characters, or their position in the word or the line.
Unfortunately, the GX font specification has not met with wide acceptance as of this writing. One reason is that it is only available for the Macintosh, and most major layout software is actively seeking cross-platform compatibility; therefore the vendors are loathe to adopt a “standard” that doesn’t have a counterpart for Windows (and other systems they may support).
Further, GX is a model which wants to take on many functions which have previously been areas where high-end layout applications have put considerable effort into adding features and value for the end user. The makers of such applications would be understandably reluctant to abandon their previous hyphenation and justification capabilities (for example) in favor of GX capabilities which are delivered “free” to the lowliest word processor which chooses to support GX.
While most existing applications will work with GX installed, if they don’t access most of its features, why should a user bother risking potential incompatibilities?
The result is that none of the biggest software vendors have released any applications which are GX-savvy. There are about a dozen programs that offer some degree of support for GX, including two page layout programs, Uniqorn and Ready-Set-Go 7 GX, and LightningDraw, a drawing package.
With Apple’s recent changes in operating system strategy, the future of GX is unclear. Apple has announced its intention to continue GX typography in the upcoming NeXT-OS-based Mac operating system (“Rhapsody”), but this will presumably be without the GX graphics model, and may be a somewhat different form of GX type. If Apple pulls it off, Rhapsody could have the effect of increasing basic GX support; it certainly worked for Apple when they fully integrated TrueType into version 7.0 of their operating system.
Unicode
Unicode is an international standard for representing a broader character set using two-byte encoding for each letter. This allows the encoding of 64,000 characters instead of 256, essentially all the characters for every language in the world, each with a unique ID. However, the Unicode specification only covers differences that have a linguistic impact, such as accented characters. It does not deal with typographic niceties such as ligatures, old style numbers, or small caps. To paraphrase Chuck Bigelow, it may seem like a metaphysical distinction, but Unicode is a character encoding, rather than a glyph encoding.
The result is that simply adding Unicode capability is very useful for non-English or multi-lingual typography. However, it does not, in and of itself, aid in dealing with the typographic issues addressed by, say, GX or OpenType.
The Unicode character encoding is directly supported by Windows NT. It is not currently supported at the system level by any other major operating system. However, OpenType (see below) is directly based on Unicode, and thus operating systems that support OpenType will get Unicode support in the process, within OpenType fonts.
National Language Support & WGL4
Windows 95 does not fully support Unicode, but has a less universal approach called National Language Support. This allows use of TrueType fonts with more than the usual 256 glyphs of Windows or Macintosh extended ASCII. For convenience, and to help preserve compatibility with older programs, the user’s selected language setting determines which glyphs are accessible from the keyboard (as in, the correct ones for the chosen language, assuming they’re in the font).
The Windows “WGL4” character set is a specific NLS set of some 652 characters, which include all the characters for every European language. This means all the usual Latin regular and accented characters, plus Greek, Cyrillic, Turkish, a host of accented characters, and IBM Linedraw thrown in for good measure. The basic Windows system fonts (Arial, Courier, Times New Roman) have all been upgraded to the WGL-4 glyph set. Only a few other TrueType fonts have this character set, such as Microsoft’s version of the Franklin Gothic family.
OpenType
This 1996 Adobe/Microsoft initiative surprised industry analysts. OpenType puts either a PostScript or TrueType outline in a TrueType-style wrapper. Applications and most operating system functions outside of the font subsystem will no longer care which type of font is in this “wrapper.” As part of the deal, Microsoft and Adobe licensed the TrueType and PostScript font technologies to each other.
The OpenType format will support all the most advanced features of existing TrueType and PostScript formats (much like GX), such as Multiple Master fonts (with PostScript outlines), multilingual character sets with full Unicode support, and extended character sets to support such typographic niceties as “true” small caps, ligatures, fractions and alternate glyphs, all within the main font. OpenType supports automatic glyph substitution so that one glyph can be substituted for a set (such as the f-f-i ligature, or many Arabic characters), or multiple glyphs can be substituted for a single one. Glyph substitution can be context sensitive, and/or activated by explicit user activity. Uses of substitution would be a swash letter that’s only used at the beginning of a word or a line, when the “swash” behavior is turned on, formatting text as true “small caps” or cycling through available alternate letter forms.
Although Seybold analysts reported on this as a victory for Microsoft and TrueType, that’s only true if you look at the publishing business in isolation. In the broad view, it is really more of a win/win/win situation. Microsoft may finally get greater TrueType acceptance in the high-end publishing market. Adobe gets PostScript font outline support at the system level in Windows, potentially making the Adobe type library more accessible to a broader range of potential buyers. Best of all, end users win by getting a single cross-platform font format, eliminating one of the largest remaining hassles for document transfer between Macintosh and Windows computers.
Apple has not yet announced support for OpenType in either Mac OS 8.x or the NeXT-based “Rhapsody OS.” However, Adobe and Microsoft seem committed to delivering a complete solution. (Ironically, the OpenType approach to putting TrueType and PostScript in a common wrapper is very much like what Apple did with QuickDraw GX and GX-enabled fonts.)
What Does the Future Hold?
It is interesting to compare the future of Open-Type to the past of GX. GX features are not actively supported by any of the leading graphics programs, and GX is actively incompatible with some of them. Will OpenType succeed where GX seems to have failed?
GX enthusiasts may say that all the features offered by OpenType can be had today in GX, and that advanced typographic support is easier if one goes with GX.
But there are several key differences which may swing the future in OpenType’s favor. First, OpenType is in no way incompatible with existing applications and fonts—it’s not the case that one must embrace it all at once, as GX attempted. Second, OpenType was created by the leading maker of business software (Microsoft) and the leading creator of graphics software (Adobe). If even only these two companies’ applications support OpenType to start with, that would be much further than GX got with mainstream applications.
On the other hand, applications that support OpenType may not do it as evenly as GX-savvy apps support that technology. With GX, an application simply lets the GX “Line Layout Manager” do all the work. With OpenType, the needed font information is available through system calls, but it is up to each application to decide what to do with it.
One thing that drives acceptance of some solution, whether GX or OpenType, is the needs of the international markets. In particular, the Asian languages such as Chinese, Japanese and Korean, which can’t be represented by a single-byte font, require something that supports larger character sets. This is essential for operating system companies such as Apple and Microsoft, and very important to Adobe, which also derives a large chunk of revenue from the Asian markets.
By mid-1998, initial OpenType font offerings, OS support, and the first actively supporting applications should appear. This is also when the full version of Apple’s Rhapsody OS is scheduled to ship. At this time it should be much more apparent how OpenType and GX support are shaping up, and whether the support and benefits of either or both are sufficiently compelling to users. In the meantime, they are both technologies worth keeping an eye on.
Conclusion
OpenType may be a savior in the font wars, but first it will have to be supported at the operating system level, and applications will need to be re-engineered to take advantage of its more whizzy features. Although existing font libraries could easily be converted directly, it is only by the combining of fonts and the laborious addition of new features that the greatest value can be added to them. This will take years. In the meantime, users still have to choose.
There are some real differences between PostScript and TrueType—although the relative advantages of each are often exaggerated by the boosters of one or the other format. Each format—and the combination of the two in OpenType—has extensions, which offer the promise of new capabilities; but these are not yet widely adopted. In practice, most users can usually use both formats, and mix them, without worrying a great deal about the differences, which are usually transparent to the final viewer.
Nonetheless, there are definitely situations in which one format or the other may be desirable, such as when particular expert sets are needed (more commonly available in PostScript fonts), when TrueType doesn’t work on a particular older imagesetter, or when maximum legibility is needed for screen display (the best TrueType fonts).
Thanks, Tom, for this excellent article. You’ll be the first Adobe employee to sport a FontSite tee-shirt. –SC |
