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Re: let's get rid of image/gif

1995-01-11 09:33:02
There is a patent-free 100% gif-compatible format.  Here's an excerpt
from the JPEG mailing list:

Date: Wed, 4 Jan 1995 03:22:34 -0500
From: ghost(_at_)aladdin(_dot_)com (L. Peter Deutsch)
To: Multiple recipients of list <jpeg(_at_)cs(_dot_)columbia(_dot_)edu>
Subject: Re: GIF and the IJG code

I'm considering taking the following approach in Ghostscript.

Consider the following encoding scheme for N-bit binary data (let's
take N=6 for the sake of exposition).  We encode N-bit data using N+1
bits for each data element, in order to allow adding two out-of-band
signals: a "sync" signal for error checking, and an end-of-data
signal.  For N=6, we use the following encoding:

       Data values: 0xxxxxx
       Sync: 1000000
       End of data: 1000001

We further require that the sync signal occur at least once every
2^N-3 elements in the data stream.  (E.g., for N=6, at least once
every 61 elements.)

This coding scheme is a simple and obvious one.  It isn't a
compression scheme; in fact, it makes the data larger.

Perhaps the MIME spec should simply point out that there are patent
concerns with image/gif (and LZW image/postscript).  Perhaps it could
also reference patent-free alternatives that are currently registered
(e.g. image/tiff with CCITT compression schemes?)

                - Chris

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