Review of Microsoft's ClearType Font Collection (2005)

The first five hundred years of typography (as opposed to calligraphy) were all about the printed page. Until recently, the most carefully designed type on computer screens was simply a placeholder for the final printed version. The promise of “what you see is what you get” was really based on a little white lie. The type on the screen would of course be coarser, and there was no hope whatsoever of faithfully reproducing the subtleties of spacing. The screens and rendering technology just couldn’t do it.

Now we are at a crossover point. A lot of people spend a lot of time reading from computer screens. Fortunately, the screens are a lot better (and still improving), and innovations such as Microsoft’s ClearType are pushing the envelope of rendering technology. Even so, most of the fonts people read on-screen are either holdovers from pre-digital print, or screen fonts excellently tuned for last year’s displays. The time is right for new fonts carefully crafted for reading on today’s screens, and those of the next few years.

Microsoft has sensed this need and has responded by commissioning a suite of six fonts optimized for ClearType. These fonts will be bundled with the upcoming Longhorn operating system, scheduled to ship in late 2006. Microsoft’s dominant market position ensures that a huge fraction of the letters projected onto eyeballs in the next decade will be renderings of these fonts.

Stephen Coles asked me to review these fonts for Typographica. Since I also work on font rendering technology, having recently developed FontFocus, I have passionate opinions about the way fonts rendered into pixels should look. The fact that my technology competes with Microsoft’s would of course disqualify me from writing as an objective journalism, but that’s not what you’ll get here.

The Technology

ClearType first shipped in January 2000 with Microsoft Reader for Pocket PC’s, to generally good reviews, and is now integrated with Windows XP. At its core is RGB sub-pixel rendering, which takes advantage of the fact that a 100 dpi color LCD panel is at heart a 300×100 dpi monochrome display with a color stripe filter. If you could get rid of the stripe filter, you’d immediately have much better resolution in the horizontal direction, which would be most useful for near-vertical stems. Another possibility would be to leave the stripe filter on and send the same image you’d send to a 300×100 dpi monochrome display, but that would result in serious color fringing. The essence of ClearType is a clever filtering technique to get rid of most of the color fringing, while retaining at least some of the resolution enhancement.

The version Microsoft will ship with Longhorn has two major refinements. First, while the old ClearType demonstrated noticeable stairstepping on near-horizontal features, now y-direction antialiasing smooths these out considerably. Ian Griffiths demonstrates this clearly.

Second, the old version of ClearType forced all positioning calculations to be done in increments of one pixel, the same as TrueType, leading to somewhat coarse spacing. The new version appears to have 1/6 pixel spacing accuracy, which looks quite a bit smoother. Further, designers don’t have to carefully hint the metrics to get good spacing.

Both refinements are welcome improvements, but at heart the technology is still much the same as shipped with XP.

The new fonts also make strong use of OpenType features such as contextual ligatures, a freedom which has until recently not been available to designers of screen fonts.

It’s also worth noting what technologies are missing, notably multiple masters (although Luc(as) de Groot designed Calibri as two weights of a Multiple Master, the interpolations aren’t shipped), and any kind of optical scaling technology. In fairness, I should point out that the nonlinear nature of ClearType filtering does improve the robustness of very thin strokes, one of the benefits of optical scaling.

Designing for Contrast

One of the most important design goals for antialiased screen fonts is achieving contrast. In the old days of monochrome rendering, contrast was excellent, but diagonals were jaggy and curves were quite distorted. Antialiasing fixes these problems but makes the letters appear soft and blurry. ClearType improves matters somewhat, but certainly doesn’t make the difficult tradeoff simply vanish.

Contrast depends on many factors, among them specifics of the typeface design. In particular, the exact orientation of a stroke matters a lot. Exact horizontal strokes render very well (assuming the font is properly hinted), but nearly-horizontal strokes don’t. You often see a near-horizontal stroke as the top of the lower bowl of the ‘g’, one of the glyphs most likely to be rendered feebly.

In addition to avoiding near-horizontals, several other principles apply to designing for ClearType:

• A slightly squarish ‘o’ renders with better contrast than a perfect oval.
• Serifs need to be robust, but a triangular or wedge shape renders just as well as a slab.
• Old-style serifs are much worse than modern or transitional (in the latter case, hints need to effectively convert them into modern).

At the same time, ClearType does a fantastic job rendering near-vertical stems, including vertical stems with subtle (Optima-like) modulations of weight, so these features are an excellent way to make designs more fluid and less constrained by the oppressive pixel grid of the pre-ClearType world.

The New Fonts

Microsoft commissioned six new fonts from designers working in close collaboration with engineers in their Advanced Reading Technologies group. Overall, these are good, solid font designs with an emphasis on what works well in ClearType. They share many characteristics: humanistic italics (as opposed to simply obliqued), a fairly high x-height (with the exception of Constantia), a large character set including both Greek and Cyrillic, and a uniform lack of near-horizontal strokes. All are slightly condensed in width.

These fonts are optimized for the screen, not for print. Aside from Constantia and Consolas, in general I would choose other fonts over the ones in the ClearType suite. Of course, these fonts will see an awful lot of use in print, and they’re not bad (vastly better than Arial, for sure). And for some applications, including mixing of Greek and Cyrillic, they may well be the best fonts available.

Constantia

John Hudson

Everybody’s favorite face will be Constantia by John Hudson. This one was designed to work well both in print and on the screen, for large bodies of text such as journals. Even though it’s a highly readable Roman font departing only slightly from the classical model, it still manages to be fresh and new. It takes some inspiration from Perpetua and Felicity (in fact, these are the only two non-MS fonts mentioned in Now Read This, a booklet published by MS to introduce the new ClearType fonts), but the triangular serifs bring to mind a chisel, and the font has enough calligraphic flavor to recall Palatino. The Greek and Russian also appear exceptionally strong to my eyes (but keep in mind I don’t speak either).

Cambria

Jelle Bosma

Largely following in the footsteps of Georgia, Cambria will be the default font in the next Microsoft Word, taking over the spot long owned by Times. It works well as a screen font, but in print I don’t find it very appealing. Stroke contrast is low, and the vertical serifs (terminals of ‘acfrsyz’ and ‘CEFGLSTZ’) have a distractingly heavy wedge shape, reminiscent of a display faces Renault and Dominante. Georgia, I think, did a better job of making the robust features work within the classical letterform architecture.

Cambria’s ‘f’ has a fairly narrow top, which means that traditional ‘fi’ and ‘fl’ ligatures would be stylistically inconsistent (especially given the relatively loose spacing). Instead, designer Jelle Bosma used the contextua