laser-lovers@uw-beaver (05/15/85)
From: imagen!geof@SU-SHASTA.ARPA
[Re: Your question of matching spacing between a phototypesetter and a laser
printer]
My understanding is that a laser-printed "helvetica" (w.l.o.g.) sample
is supposed to match up on paper to a phototypeset "helvetica" sample
such that the individual character positions are the same. Independent
of the printer involved, a correctly tuned font should have this
property, at least for samples in a size range where single pixel width
errors are small relative to character size (maybe 10-12 point and
larger at 300 dpi, although I haven't tried it). The characters
themselves will be a slightly different shape, because they have to
"look good" at a lower resolution, but the spacing should match.
Some things to watch for:
- phototypesetters will often optically scale one or more "design size"
of font, so a phototypeset character 10 points high might not match a
laser-printed character 10 points high. You should check that the
"design size" and the "actual size" of the character are compatible
between the laser and phototypesetter.
- at smaller resolutions, quantization error makes it very hard for
the laser printer to make the characters look good. There is an
inevitable design choice to be made (at least on the defaults --
with deference to B. Reid) of whether the intercharacter spacing
should suffer or the character widths. In the former case, the
output looks funny. In the latter case, the output won't match
a phototypesetter closely.
If these problems bite you, you can still use the laser printer as a
proof device for the phototypesetter by individually positioning each
character (or by modifying the character widths, where this is possible
-- this amounts to the same thing). I remember that some group at Bell
Labs was doing this some time ago. The output of the laser printer was
legible and not pretty (it used bad but compatible character spacing),
but it gave an extremely good indication of what the phototypesetter
would produce, and took a lot of strain off the slower device.
- Geof Cooper
Usual disclaimer:
<I work for Imagen. The above is a personal statement, not authorized by
my employer. I tried to keep it independent of particular printers
languages or companies, anyway>