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From: sdh@joevax.UUCP (The Doctor)
Newsgroups: net.micro.mac
Subject: laser writer oddities
Message-ID: <234@joevax.UUCP>
Date: Tue, 12-Aug-86 13:27:27 EDT
Article-I.D.: joevax.234
Posted: Tue Aug 12 13:27:27 1986
Date-Received: Wed, 13-Aug-86 09:14:54 EDT
Distribution: net
Organization: Bell Communications Research Inc., Morristown, NJ
Lines: 37


The laser writer is supposed to give you what-you-see-is-what you get
for MacPaint, right?  I don't think so.

It seems that on a LaserWriter+,  when printing a Macpaint document, it
looks for certain patterns to reproduce in fine detail.

For example, let the character X, represent a pixel on the LaserWriter. And
Let Macintosh pixels be equal to 4 X's (a 2x2 block).

If you have this pattern in Macpaint:

	XX  XX
	XX  XX
	  XX  XX
	  XX  XX

you should get the same thing from the laser writer. Instead it generates:

        X X X X
	 X X X X
	X X X X
	 X X X X

Theoretically, these are equivalent, ie, the same pixel density. The trouble
arises when you don't have large areas of patterns that can easily be
recognized by the LaserWriter Driver.  What results is that pictures do not
come out looking like they do on the screen, in fact the pattern aliasing
makes digitized pictures look out and out wrong, since the way pixels are
arranged in blocks severely effects the way levels of gray are preceived.

Is there any way to get around this quirk?  Is there a program that will
reproduce Macpaint pictures on a LaserWriter+ doing a true pixel for pixel
mapping instead of pattern matching?

Steve Hawley
joevax!sdh