Posted by Christopher Slye

 Comments (8)

Created

September 1, 2011

A month ago, Typekit rolled out improved font rendering on Windows, and began serving certain typefaces in OpenType CFF (PostScript Type 1) format*, instead of the more customary TrueType format. Yesterday, they began serving selected Adobe Web Fonts as CFF as well, and the result is noticeably better appearance for large text sizes.

Typekit observed that, although TrueType fonts tend to look better at text sizes with Microsoft’s ClearType subpixel antialiasing in Windows GDI rendering environments (still the majority of web viewers out there), there can be distracting pixelation on some diagonal features at large point sizes. Their clever solution is to serve CFF fonts for certain display designs which are unlikely to be used at smaller text sizes. GDI will only apply grayscale antialiasing to Type 1 fonts, resulting in smoother appearance. On Mac OS X and in some newer Windows environments (DirectWrite, to be more specific), the quality is essentially the same as TrueType.

Type rendered in Windows GDI in TrueType format (left) and CFF (right). (Image from the Typekit Blog.)

Large letters rendered in Windows GDI from TrueType outlines (left) and CFF (right). (Image: the Typekit Blog)

Here at Adobe, we’re obviously pleased to see CFF fonts served where it makes sense to do so. We think CFF has certain qualities and advantages which often make it a better choice — on the web and elsewhere. (Later this month I will be speaking more about this at the ATypI conference in Reykjavíc, Iceland.) To read more on this subject from Typekit and to see more examples, see yesterday’s post on the Typekit Blog.

* When referring to “PostScript,” “Type 1″ or “CFF” fonts, what I really mean is OpenType with this outline format in it. OpenType fonts can contain outlines in either CFF or TrueType format. CFF — the Compact Font Format — is a variation of the original Type 1 font format, created by Adobe along with the PostScript language.

COMMENTS

  • By Richard Fink - 7:49 AM on September 3, 2011  

    Christopher,

    One question: IE 6, 7, and 8 require TrueType fonts compressed as EOT. So, how does this technique work in those versions of IE, or does it not?

    Rich

    • By Christopher Slye - 11:04 PM on September 3, 2011  

      Hi Rich. IE8 accepts CFF fonts in EOT, so I believe Typekit serves them that way — and TrueType to previous versions. (I will check with them to confirm that.)

  • By Richard Fink - 9:19 PM on September 4, 2011  

    >IE8 accepts CFF fonts in EOT

    I have never heard it mentioned before that an EOT could be made from anything but a TrueType font. Especially for IE8. (IE9 will accept an OTF CFF raw with embedding bit set to 0 or wrapped as a WOFF)
    Wondering how a CFF wrapped up as an EOT is created…. and how it looks….

    Any info appreciated. Thx.

    Rich

    • By Christopher Slye - 9:35 AM on September 5, 2011  

      Amusingly, my Google search on this subject returned exactly one hit, in which you and I previously discussed this (but not in detail). Since the EOT format was published by Microsoft, it became clear that the format allows for CFF — the problem is that Microsoft’s WEFT doesn’t work with CFF, and versions of IE before 8 don’t either. Back when EOT Lite was on the table, we built CFF-in-EOT fonts here to test them, and verified that they work in IE8. I’ve not recently tried to wrap a CFF in EOT, but I’d guess that one or more EOT-building tools out there would do it.

      Anyhow, EOT/CFF does not look great in IE8, since it’s still CFF being rendered with GDI.

  • By Richard Fink - 2:23 PM on September 5, 2011  

    Thanks Chris. I thought I was going nuts. (Nuts, yeah, but not as far as this is concerned!)
    EOTFAST will not create a true compressed EOT with a CFF file. At least not the way it’s written now.
    I don’t know about Ascender’s EOT lite tool but I can dig it out and give it a try and let you know.
    One thing I did try was a TTF with PS outlines, no hinting. It DID NOT trigger smoothing in IE8. I did not try messing with GASP table settings. I guess that’s next.
    I think there’s some benefit to be had by feeding CFF files to Chrome, and FF on Windows. Obvously, Typekit has some confidence in it.
    The jury’s still out on IE, though. Perhaps a visit to Typekit’s site for a look at the fonts to which this technique has been applied will bring answers.

    I’m pretty sure I posted the same basic question about CFF in IE<9 on Typekit's blog but no answer that I'm aware of.

    Thanks. If I find out something, I'll post.

  • By Tim Brown - 7:49 AM on September 6, 2011  

    Hi Rich,

    PostScript-based outlines make a difference in all Windows browsers except IE<7. The reason PS-based outlines don't affect IE<7 is because the EOT format, used in those browsers, requires TT-based outlines. IE8 supports PS-based EOT files, but not on XP.

    Tim

  • By Richard Fink - 6:22 AM on September 7, 2011  

    Thanks Tim. Musta got my subscriptions tangled.
    So, PS outlines on IE8/XP don’t work. Yeah, this makes sense.