Phinney on Fonts

It’s not a “screen font” any more

Written by

Thomas Phinney

in

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Funny, the other day I had just finished a first pass at reviewing and revising the Extensis document on “Best Practices for Font Management in Mac OS X,” when a non-​Extensis colleague asked me something about PostScript Type 1 fonts: whether Windows .pfm and .pfb files were pretty much equivalent to Mac screen and printer font files.

What was funny to me was that only half an hour earlier, I had just been adjusting the language about “screen fonts” and “printer fonts” in the Extensis doc.

Anyway, here’s what I said:

First, on *both* Mac and Windows, the phrases “printer font” and “screen font” make no sense any more when referring to the pieces of a Type 1 font. The last time those phrases made sense was at the beginning of the 1990s, before everyone started using ATM, which scaled the outline font (then called a “printer font”) for display on screen. This function has been long since taken over by the Mac and Windows operating systems around 1999-2000.

Heck, Mac OS X isn’t even capable of using the bitmaps from the font suitcase for screen display at all, so it really isn’t a screen font any more.

So, the “screen font” isn’t used on screen, and the “printer font” is used both on screen and on printers.

Which is why I prefer to use the terms “font suitcase” and “outline font.”

The font suitcase for a Type 1 font contains kerning information, which is useful, and bitmaps, which are required, but not actually used anywhere any more… it’s just that you need at least one bitmap size per font. BTW, one font suitcase can contain bitmaps for multiple outline fonts.

The outline font is what it sounds like, the actual scalable outlines of all the glyphs in the font, as well as some platform-​independent info such as the PostScript FontName, FullName, yadda yadda.

Oddly, both the suitcase and the outline font contain advance widths—the amount of space allotted for each glyph, including white space on either side of it.

Finally, to answer my colleague’s question? Yes, the Windows .pfm and .pfb files are pretty much equivalent to the Mac font suitcase and the outline font (exactly equivalent in the case of the outline font and the .pfb). The .pfm file doesn’t have bitmaps, but it has other platform-​specific info, like the font suitcase.

Of course, font suitcases can also be containers for Mac TrueType fonts, but that’s another story….

[updated 27 Apr 2009 to clarify OS X not using bitmaps at all]

Comments

3 responses to “It’s not a “screen font” any more”

  1. santi

    Aren’t the bitmaps used to display small sizes?

    [Nope, not any more. Not since OS X 10.0 on Mac, nor in recent Windows rendering systems. – T]

    What makes me think so is that when I edited the glyphs’ vectors from a font editing application and tried to see the result in MS word, smaller sizes looked horrible – even up to 16 points, they just suck. Do you by any chance make/​edit fonts and know a way to fix this? 🙂

    [Yes, I do, but the answers aren’t simple. You don’t say what operating system you’re on, or what font editor you’re using, or what font you modified, so it’s hard for me to give very specific advice…. Broadly speaking, something called “hinting” is the key factor in rendering at small sizes on screen. Automatic hinting can do okay, but not great. A really heavily hinted TrueType font (for example, a system font on Windows) will pretty much always suffer in rendering quality if you try to edit it at all. If the font has PostScript style outlines, automatic or simple manual hinting can do fine. You’ll need to do some more research/​reading to learn more, though. – T]

  2. Mark

    Interestingly, people keep seeming to forget that there are still printer only fonts, however these are used for label printers (from Zebra and Datamax for instance) and the like. Those Printer Fonts do not have an equivalent on screen version so they often default to the same on-​screen font. They exist because they are built into those printers and therefore allow for significantly faster printing when compared to font files such as ttf and otf.

  3. Mark

    FYI these printer only fonts are often called “Printer Device Fonts” or simply “Device Fonts”.

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