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From: olsen@hpfcdq.HP.COM (John Olsen)
Newsgroups: comp.graphics
Subject: Re: Scaling Transformation on Bitmap Characters.
Message-ID: <390053@hpfcdq.HP.COM>
Date: 13 Nov 90 17:43:25 GMT
References: <1990Nov5.022837.15506@ucselx.sdsu.edu>
Organization: Hewlett-Packard - Fort Collins, CO
Lines: 29

lance@motcsd.csd.mot.com (lance.norskog) says:
>I'd like to suggest another approach to scaling bitmaps.  I haven't
>seen it mentioned anywhere but I'm sure someone smarter than me
>thought it up first.

>			Perceptron Scaling

>This scheme only works for scaling in increments of small whole numbers.
>In essence, you build a library of bit map pairs, and hunt for matches.
>...

You're describing something similar to an item I wrote for the book Graphics
Gems (Smoothing Enlarged Monochrome Images).  My method uses rules sort of 
like you describe, but it the technique isn't limited to integer scaling 
factors.

It doesn't particularly apply to the problem described in the base note,
because although it will smooth the edges as desired, it will do nothing to
change the thickness caused by scaling a small character up to a big
character.

You could accomplish this thinning with a very large set of rules as 
described in Lance's previous posting, but it would take a lot of work 
to create those rules, and they would only work for the scaling factor 
they were designed for.

John M. Olsen, Graphics Technology Division  (303)229-6746
olsen@hpfcjo.HP.COM, olsen@hpfcdq.HP.COM
Hewlett-Packard, Mail Stop 74, 3404 E. Harmony Road, Ft Collins, CO 80525