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Re: Is Apple's patent valid?

From: Glenn Randers-Pehrson <glennrp@home.com>
Date: Thu, 04 Oct 2001 12:14:04 -0400
Message-Id: <3.0.6.32.20011004121404.00d1f100@netmail.home.com>
To: www-patentpolicy-comment@w3.org
Chris Lilley wrote:
>Cool. I assume that this is the Dec 1991 reease of NetPBM, so the code
>dates from at the latest, 1 December 1991 which is five months before
>the patent application on 8 May 1992. Since NetPBM was extremely widely
>announced and deployed, and has freely available source, it is a good
>prior art claim.

Yes, pnmarith is in the 1991 release.

>Could you post a command line that takes A.ppm, does channel by channel
>composition using channels from B.ppm and composites the result over
>C.ppm? Where A, B and C are any rgb ppm images.

OK but you'll need to hold me harmless for infringement of the Apple
patent.  I grant everyone a royalty-free license to use this script for
research purposes only.  I make no guarantee that using this script will
not violate third-party intellectual property claims or that the script
is suitable for its intended use.  This license expires 11 October 2001.

#!/bin/sh

# 3-way blending with separate alpha channel per color
# (infringes on Apple patent 5379129)
# Copyright 2001, Glenn Randers-Pehrson, all rights reserved.
# Usage: blend3 width height alpha.ppm file1.ppm file2.ppm
# blended file is on standard output

pnmmake "#ffffff" width height > ffffff.ppm
pnmarith -mult $3 $4 > alpha-times-alpha.ppm
pnmarith -subtract ffffff.ppm $3 > 1-minus-alpha.ppm
pnmarith -mult 1-minus-alpha.ppm $5 > alpha-minus-1-times-b.ppm
pnmarith -add alpha-times-alpha.ppm alpha-minus-1-times-b.ppm
rm alpha-times-alpha.ppm 1-minus-alpha.ppm alpha-minus-1-times-b.ppm
rm ffffff.ppm

Glenn
Received on Thursday, 4 October 2001 12:16:49 GMT

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