Typekit has announced that it is now serving PostScript versions of certain fonts in order to work around a problem with Windows rendering.

Those who haven’t upgraded to the DirectWrite type rendering that comes with Internet Explorer 9 and is an option in Firefox 4 are still using the GDI rendering engine, which has anti-aliasing that only works in one direction.

With certain fonts in larger sizes, this causes the type to have jagged, unappealing outlines.

But a quirk allows Typekit to work around the problem. By serving PostScript instead of TrueType versions of certain fonts, grayscale antialiasing is used instead — smoothing out the jagged lines.

This workaround has been rolled out for the fonts Bello Pro, Calluna, Lapture Display, and Quatro. Typekit is working with foundries to identify other fonts that could benefit from this hack.

If you’ve experienced unsightly rendering under Windows with some of your favorite fonts, it looks like your problem could soon be solved for good.

The image above shows Bello Pro with GDI anti-aliasing on the left and grayscale on the right — a marked improvement.