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From: jerem@tekgvs.UUCP (Jere Marrs)
Newsgroups: comp.sys.amiga
Subject: Re: PageSetter -- HELP Needed.
Message-ID: <1973@tekgvs.UUCP>
Date: Thu, 25-Dec-86 18:43:20 EST
Article-I.D.: tekgvs.1973
Posted: Thu Dec 25 18:43:20 1986
Date-Received: Fri, 26-Dec-86 05:35:42 EST
References: <7085@decwrl.DEC.COM> <3381@garfield.UUCP>
Reply-To: jerem@tekgvs.UUCP (Jere Marrs)
Organization: Tektronix, Inc., Beaverton, OR.
Lines: 43
Keywords: PageSetter,Proportional spacing, kerning

>
>BTW, what exactly does the "kerning" selection in Font-Ed do? How does this
>relate to presentation on the screen and/or printer?
>
>John

	I only recently learned this, so I have all of the arrogance of recent
learning.

	The terms "kerning" and "proportional spacing" are often confused.
Proportional spacing means that letters of narrower width are given 
proportionately smaller spacing and therefore fill space more efficiently and
more aesthetically. An "i" takes fewer 'microspaces' than an "m." This is how
typesetting differs from a normal typewriter. Back in the old days when type-
setters used to cast their own Woods-Metal fonts for each publication, they
found that when certain letters occurs in particular sequence, even more space
can be used efficiently. For instance, if a 'V' occurs after an 'A', then they
can be pushed closer together. So AV takes less space than it would if each
letter were given the full number of microspaces attributed to it 
proportionally. If you imagine each letter in a rectangle whose width is equal
to its number of microspaces, then kerning allows these rectangles to overlap.
So, clearly, kerning requires that the actual sequence of the letters be
taken in account in spacing. Proportional spacing considers only the next 
letter to be printed.

	I assume FontEd considers the sequence of letters and allows them to
'fit' together more closely. A computer and a laser printer (or other bit-
mapping printers) are ideally suited for this.

	I thought that the person who observed that desk-top publishing (let's
find another term) will require new things of editors and word processors, hit
upon a fundamental truth. We will need programs that deal with text-formatting
'objects' rather than print pitch, margins, indentation, etc.. Such an object
could be a paragraph, a header, an indented section, or graphics, etc..  We 
would then create a base of these objects and then assign them to spaces in
the document, letting the formatting program worry about the details including
the proportional spacing and kerning. It would be a more interactive, WYSIWYG
troff. The graphic orientation would obviate the 'dot' directives.

						-Jere
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