Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!natinst!rpp386!woody
From: woody@rpp386.cactus.org (Woodrow Baker)
Newsgroups: comp.lang.postscript
Subject: Re: ruler.ps - an inch/point ruler of your very own
Summary: probably
Message-ID: <17673@rpp386.cactus.org>
Date: 16 Jan 90 13:23:13 GMT
References: <21772@uflorida.cis.ufl.EDU> <1990Jan14.180821.18711@trigraph.uucp> <1728@gannet.cl.cam.ac.uk>
Organization: River Parishes Programming, Plano, TX
Lines: 26

> such any such bit-grubbing; more likely it was `keep it simple for the users'.
> Anyone from Adobe care to say?
> 
> One shouldn't forget, in this context (1) the inter- and intra-printer  
> reproducability of the bit density (2) paper shrinkage. Such differences
> are liable to wipe out the difference between 72 ppi and 72.27 ppi.

You may well be right. Paper shrinkage probably doesn't effect things
so much, especially with the custom laser papers.  The inter/intra printer
spacing, however could be quite significant.  I have seen some strange
results.  Consider a .5 % tolerance.  at 300 dpi you could be off as much
as +/- 1.5 dots.  A more logical tolerance would be 5%, at least most of
the components would have that tolerance rating, and I'd suspect that the
mechanical tolerance would be a tad closer than that, but that gives you
15 dots over an inch.  considering that 4.1666 or so dots per point, and
we have 3.6 points diffrence over an inch.  A  1% tolerance would be nearly
1 point.  That's pretty small, but I suppose it is possible.  There is 
more likely, going to be a greater effect due to spot size of the laser than
anything.  That is adjustable a bit, and the power to the laser is adjustable
.  I have seen some significant problems with the laser drive not being 
adjusted right in the  repair department where I used to work.

Cheers
Woody