GoKawiilWritten by Raph Levien on April 14, 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.
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