Relationship between OpenType fonts and PostScript printers, and impact on printing performance?

Question

In the pre-OS X days, there was an important distinction between bitmap fonts and PostScript fonts, and between QuickDraw printers (the Mac equivalent of "Winprinters") and much more expensive PostScript printers. If you wanted to use a PostScript font with a PostScript printer, you needed to have installed on your computer the bitmap equivalent of one of the standard preinstalled PostScript fonts. Later, it became more common to make sure that the PostScript font "suitcase" was in the right place to download to the printer at print time, and use Adobe Type Manager to display it antialiased on the screen.

In contrast, most fonts installed with OS X by default and available for purchase are either OpenType or TrueType format. Many inexpensive laser printers now speak PostScript level II or level III, and in consequence include an even larger assortment of built-in PS fonts than PS level I printers such as the original LaserWriters.

According to Adobe, OpenType is a superset of the PostScript font format, and OpenType is supported by PostScript printers:

OpenType development has improved both the support of Type 1 on Windows and the support of TrueType in the PostScript environment, ensuring that customers who use PostScript printers will have the best possible experience regardless of the font type used. Support for OpenType is part of the PostScript printing system, with the support of the latest AdobePS™ printer drivers and Adobe Type Manager.

Exactly what "support for OpenType" at the beginning of the second sentence means here is pretty unclear to me, though. If I want to use a PostScript printer with OS X, will it make a difference in printing speed or quality if I use a font on the computer that is (or is not) in the list of fonts on the printer? How does this work?

• For example, if I print a TextEdit document in (OpenType) Helvetica to a networked LaserWriter, does OS X send PostScript code to the printer, which then uses its own built-in Helvetica font data in ROM to construct the glyphs on the page?
• What if I use an OpenType font that's on the computer but not on the printer? Does the font get translated into a PostScript font then downloaded to the printer (presumably a slower process just like it was in the pre-OS X days), which then prints with it as if it were built-in?
• Or in the previous case do the OpenType glyphs get rasterized on the OS X side and then sent to the printer as a bitmap?
• In either case, how does this affect the quality of printed output?
• Whether the OpenType font is downloaded as a PS font or as a bitmap, I'm guessing this would take a lot more memory on the printer side than just sending PostScript code. Should I worry about running out of printer memory (or at very least my document taking a long time to print) just as in the pre-OS X days?
• Is it still worthwhile to seek out a printer with a built-in hard drive to store downloaded fonts, if I'm going to be doing a lot of printing with fonts that aren't part of the native printer-resident set?
• Are there printers that get around some or all of these problems by coming bundled with OpenType fonts as part of their firmware, or at least printing with OpenType fonts directly? This seems like the natural next step beyond inexpensive networkable printers with Postscript Level III support such as this Okidata model.

Answer 1

1. Printer-installed fonts tend not to be used at all, as PostScript output from MacOS (and PDFs) use unique names to reference the Font data that they contain, e.g. "Helvetica-Bold+AAXYZ".
2. There is no benefit to having a printer that stores font data, because the font names in the printer won't match the unique names in the PS output. Also, the amount of data saved is in the order of Kb, and negligible in terms of file size and performance.
3. The PostScript output from MacOS encodes the glyph data from PostScript, OpenType and TrueType fonts in a variety of ways within the data stream. It is not rastered beforehand.
4. I suspect that most laser printers these days contain ample memory, compared to those in 'pre-OS X days'. Some printers, particularly larger, 'network' devices, have memory expansion slots where you can add DIMMs.

In short: you do not have to worry about any lack of quality or performance by using OTF or TT fonts, compared to Type1 PS fonts.

Interestingly, I have recently learnt that because of the more mathematically complex method of describing curves in PostScript OTF fonts, compared to TrueType fonts, that PS OTF fonts can be slower to display on screen than TT fonts. On today's fast CPUs, the effect is only noticeable on very large graphical documents, and can be in the order of 10ths of a second. Whether this similar affects the 'thinking time' for a printer, I don't know.