Path: utzoo!attcan!uunet!jarthur!usc!samsung!emory!ogicse!zephyr.ens.tek.com!tekcrl!scott
From: scott@tekcrl.LABS.TEK.COM (Scott Huddleston)
Newsgroups: comp.graphics
Subject: Re: shrinking a bitmap by 3
Message-ID: <6543@tekcrl.LABS.TEK.COM>
Date: 26 Jul 90 07:47:01 GMT
References: <32071@cup.portal.com>
Reply-To: scott@tekcrl.LABS.TEK.COM (Scott Huddleston)
Distribution: na
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 13

In article <32071@cup.portal.com> DeadHead@cup.portal.com (Bruce M Ong) writes:
.>I am writing a program that would shrink a bi-level bitmap by three.
.>... My original approach is to 
.>take 3 bits at a time and if there are two black bits, then the resultant
.>bit will be set, otherwise the resultant bit is a white bit. The image is
.>not shrunk vertically.  However, this is tooo slow...

Sounds like you want table lookup.  Grab 12 bits at a time and index into
a table giving the 4 shrunk bits.  Precompute your table for all possible
12-bit combinations.
-- 
Scott Huddleston
scott@crl.labs.tek.com