AWARE SYSTEMS
TIFF and LibTiff Mail List Archive

Thread

1997.05.23 20:03 "PackBits confusion", by Richard J. Kinch
1997.05.30 18:29 "Re: PackBits confusion", by Sam Leffler
1997.05.30 19:14 "Re: PackBits confusion", by Richard J. Kinch
1997.05.30 22:02 "Re: PackBits confusion", by Helge Blischke

1997.05.30 22:02 "Re: PackBits confusion", by Helge Blischke

When I recently implemented a TIFF reader in PostScript, I also implemented PackBits decoding using the RunLengthDecode Filter. The PostScript "red book", section 3.13, RunLength{De|En}code Filter states that the code 128 (0x80) is treated as an EOD (End Of Data) marker. I did some tests with Macintosh (Photoshop) images written with PackBits compression, and, appending 128 to the end or the stream, the images were properly processed. So I'd think treating this code as a noop should be the only correct interpretation.

Helge

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H.Blischke@srz-berlin.de
H.Blischke@srz-berlin.com
H.Blischke@acm.org