# Acknowledgments and Other Issues

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## Acknowledgements

The LZW algorithm is derived from the compress program (the proper attribution is included in the source code). The Group 3 fax stuff originated as code from Jef Poskanzer, but has since been rewritten several times. The latest version uses an algorithm from Frank Cringle -- consult `libtiff/mkg3states.c` and `libtiff/tif_fax3.h` for further information. The JPEG support was written by Tom Lane and is dependent on the excellent work of Tom Lane and the Independent JPEG Group (IJG) who distribute their work under friendly licensing similar to this software. Many other people have by now helped with bug fixes and code; a few of the more persistent contributors have been:

        Bjorn P. Brox		Dan McCoy
        J.T. Conklin		Richard Minner
        Frank D. Cringle		Richard Mlynarik
        Soren Pingel Dalsgaard	Niles Ritter
        Steve Johnson		Karsten Spang
        Tom Lane

(my apology to anyone that was inadvertently not listed.)

## Warning

It appears that Unisys is actively pursuing copyright control on the LZW compression algorithm. In particular, users of the LZW compression within the TIFF framework. For this reason the TIFF 6.0 spec states that LZW compression is not recommended. It is unclear at this time what compression algorithm will be used in place of it. I have no idea what this means to you or to this library. I make no warranty or guarantees with regard to the LZW support in this library.

## Use and Copyright

Silicon Graphics has seen fit to allow me to give this work away. It is free. There is no support or guarantee of any sort as to its operations, correctness, or whatever. If you do anything useful with all or parts of it you need to honor the copyright notices. I would also be interested in knowing about it and, hopefully, be acknowledged.

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    Copyright (c) 1988-1996 Sam Leffler
    Copyright (c) 1991-1996 Silicon Graphics, Inc.

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