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Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!samsung!olivea!tardis!jms
From: jms@tardis.Tymnet.COM (Joe Smith)
Newsgroups: comp.graphics,comp.compression
Subject: Re: gif encoding questions
Message-ID: <1714@tardis.Tymnet.COM>
Date: 12 Apr 91 02:36:12 GMT
References: <1991Apr9.142255.186@unhd.unh.edu> <1991Apr10.095103.26252@ukpoit.co.uk> <1991Apr11.213950.16265@unhd.unh.edu>
Reply-To: jms@tardis.Tymnet.COM (Joe Smith)
Organization: BT Tymnet, San Jose, CA
Lines: 22

In article <1991Apr11.213950.16265@unhd.unh.edu> rg@msel.unh.edu (Roger Gonzalez) writes:
:When looking at grayscale 256 GIFs, I would expect
:>>00 00 00 01 01 01 02 02 02 03 03 03 ... FE FE FE FF FF FF
:but have seen (in ppmtogif results, for example)
:000000   47-49-46-38-37-61-00-02   00-02-E7-00-00-00-00-00   GIF87a@B@B.@@@@@
:000010   C9-C9-C9-8F-8F-8F-55-55   55-1B-1B-1B-E4-E4-E4-AA   ......UUU[[[....
:000020   AA-AA-70-70-70-36-36-36   FF-FF-FF-C5-C5-C5-8B-8B   ..ppp666........
:000030   8B-51-51-51-17-17-17-E0   E0-E0-A6-A6-A6-6C-6C-6C   .QQQWWW......lll
:000040   32-32-32-FB-FB-FB-C1-C1   C1-87-87-87-4D-4D-4D-13   222.........MMMS
:
:And I was wondering why the screwy ordering.  Sorry if I wasn't clear.

Have you tried creating a histogram of those files?  Try counting how many
pixels use color 0, how many pixels use color 1, etc.  If it turns out
that most of the pixels in the decoded picture use color 0, then that
would explain the screwy ordering.

-- 
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