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From: parkern@jacobs.CS.ORST.EDU (Neil Parker)
Newsgroups: comp.sys.apple2
Subject: Re: //gs graphics/music
Message-ID: <1990Nov13.091802.1912@scion.CS.ORST.EDU>
Date: 13 Nov 90 09:18:02 GMT
References: <160@generic.UUCP>
Sender: @scion.CS.ORST.EDU
Reply-To: parkern@jacobs.CS.ORST.EDU (Neil Parker)
Organization: The Universal Society for the Prevention of Reality
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Nntp-Posting-Host: jacobs.cs.orst.edu

In article <160@generic.UUCP> taob@pnet91.cts.com (Brian Tao) writes:
>[stuff deleted]
>     DeluxePaint II saves its graphics in a format called Apple Preferred
>Format (APF).  It uses compression to shrink the size of the file, so you
>would need the source code for the compression algorithm.  I'm pretty sure it
>uses Huffman, but you better check the tech notes to make sure.

Actually, Apple Preferred Format uses the Miscellaneous Tool Set routine
_PackBytes ($2603) to do the compression.  _PackBytes uses a form of run-
length coding for compression--a bit less sophisticated than Huffman.

If memory serves, each row of the image is compressed separately.

Recommended reading:  File Type Note for filetype $C0 (available at finer
Apple II ftp sites everywhere), and the Apple IIGS Toolbox Reference:
Volume 1 (for information on _PackBytes and its companion _UnPackBytes).

               - Neil Parker
--
Neil Parker                 No cute ASCII art...no cute quote...no cute
parkern@jacobs.cs.orst.edu  disclaimer...no deposit, no return...
parker@corona.uoregon.edu   (This space intentionally left blank:           )