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From: dan@sics.se (Dan Sahlin)
Newsgroups: comp.graphics
Subject: Re: Mac PICT2 specs, a trade secret?
Message-ID: <1990Jul15.131748.11053@sics.se>
Date: 15 Jul 90 13:17:48 GMT
References: <4421@milton.u.washington.edu> <567@dg.dg.com>
Sender: news@sics.se
Organization: SICS, Swedish Inst. of Computer Science
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bruce@archive.rtp.dg.com (Bruce Kahn) writes:

>  You can FTP the specs from apple.com [130.43.2.2] from the /pub/dts/mac
>directory (or wherever it is under /pub).

I looked at the files, and there are just some test PICS which you can try
your software on and no documentation.

In Inside Macintosh, there are descriptions of the formats, but I have yet
failed to find any description on how the 32-bit and 16-bit color pictures
are compressed.  All I know that some kind of run-length code is used.  As
the software for compressing and decompressing the pictures are included
in the 32-bit Mac software, this is not a problem on a Mac.
But keeping the compression algorithms secret makes it impossible to unpack
the on anything but a Mac.

I wonder if it is intentional from Apple to keep the compression as a
trade secret, or that they simply cannot imagine anyone trying to create
and read PICS on anything but a Mac?

	/Dan Sahlin
email: dan@sics.se

PS.  Does anyone have any ideas how the dithering is performed in 32-bit
Color Quickdraw?  It seems to work very well, and I can display a dithered
version of color pictures even on a black and white Mac SE/30.
Unfortunately this feature is for some reason disabled on a Mac Plus.