Users have reported broad and reproducible issues with font rendering after installing Mac OS X 10.6.7, the most recent update to the Mac operating system. In attempting to address potential security weaknesses, Apple seems to have broken the way certain fonts are encoded.
User Kurt Lang, posting on Apple’s support forum, identified a specific problem affecting OpenType fonts that contain PostScript font data. The OpenType format accommodates both PostScript and TrueType data, so not all OpenType fonts are affected; as a rule, but with exceptions, PostScript-based OpenType fonts are those with the .otf extension. They include Adobe’s popular Pro series fonts, such as Myriad and Minion.
PDF and EPS files generated using these fonts under 10.6.7 will display correctly in Apple’s Preview app but not in Adobe Reader or Acrobat. The problem is with the way files are encoded, not just the display, so these files will also display and print incorrectly when shared with other users. Printing directly from apps is also affected.
The issues only seem to affect software that relies on Mac OS X’s built-in font rendering, for example when using the option to save as PDF from the Print dialog box. Apps with their own rendering engines, including Adobe InDesign, shouldn’t suffer from the bug. However, Flash Professional developers have reported problems.
Users concerned about the issues should hold off installing 10.6.7 until a further update brings a fix. Although, like most updates, it addresses security concerns, these are not classed as critical. After installation, users can roll back to 10.6.6 via Time Machine or by reinstalling 10.6 Snow Leopard from the original DVD and then applying the Mac OS X 10.6.6 Combo update.
