Path: utzoo!attcan!uunet!ginosko!usc!apple!oliveb!tymix!opus!jms
From: jms@opus.uucp (Joe Smith)
Newsgroups: comp.sys.amiga
Subject: Re: Neptune Voyager Pix directly viewable on Amiga
Summary: They use 8 bits but have only 16 shades of gray
Message-ID: <2641@tymix.UUCP>
Date: 2 Sep 89 22:14:46 GMT
References: <21728@cup.portal.com> <2497@pur-phy>
Sender: news@tymix.UUCP
Reply-To: jms@tardis.Tymnet.COM (Joe Smith)
Organization: Tymnet NTD, San Jose CA
Lines: 28

In article <2497@pur-phy> murphy@newton.physics.purdue.edu.UUCP (William J. Murphy) writes:
>Thad, you mentioned using Digi-View 3.0 to bring up the Voyager pics,
>for those who don't have DV3, has anyone put together the pics into an 
>IFF HAM or H-Res image?  Although HAM will sacrifice some resolution,
>it will allow more gray scale approximations.

Even though the pictures are store using on byte per pixel, every other
nibble is zero.  Only 16 out of the possible 256 levels are used.  Therefore
no detail is lost when they are converted to a 640x480x4-bit-plane IFF
hi-res picture.  The end result is not HAM format.  (Thad has posted a
follow-up with further details.)

However, not many display programs handle that much vertical overscan.  Most
truncate the image at 420 or 440 lines.  Dpaint3 reads the image in OK, but
you have to use the arrow keys to see the top and bottom.  So far, I have
only found 2 programs that display all 480 lines properly: DigiView 3.0 and
ShoWiz 2.0.  I don't have a copy of Ushow to try.

One other warning: Fred Fish put a note on the version of uncompress in
his library that states that uncompress sometimes fails to uncompress
large files.  Symptoms are: 1) infinite loop writing garbage to the disk,
2) trashed free-list (AVAIL reports 29megabytes of memory free), or
3) all floppy drive select lights go on and the Amiga hangs.  I am having
problems with spots, tritonwhole, and twocresc.
Joe Smith (408)922-6220 | jms@antares.Tymnet.COM or jms@tymix.Tymnet.COM
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San Jose, CA 95161-9019 | narrator.device: "I didn't say that, my Amiga did!"