$Id: tiffmedian.1,v 1.4 2016-09-25 20:05:52 bfriesen Exp $

Copyright (c) 1990-1997 Sam Leffler
Copyright (c) 1991-1997 Silicon Graphics, Inc.

Permission to use, copy, modify, distribute, and sell this software and
its documentation for any purpose is hereby granted without fee, provided
that (i) the above copyright notices and this permission notice appear in
all copies of the software and related documentation, and (ii) the names of
Sam Leffler and Silicon Graphics may not be used in any advertising or
publicity relating to the software without the specific, prior written
permission of Sam Leffler and Silicon Graphics.

THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
OF THIS SOFTWARE.

tiffmedian - apply the median cut algorithm to data in a TIFF file tiffmedian [ options ] input.tif output.tif tiffmedian applies the median cut algorithm to an RGB image in input.tif to generate a palette image that is written to output.tif . The generated colormap has, by default, 256 entries. The image data is quantized by mapping each pixel to the closest color values in the colormap.

-c Specify the compression to use for data written to the output file: none for no compression, packbits for PackBits compression, lzw for Lempel-Ziv & Welch compression, and zip for Deflate compression. By default tiffmedian will compress data according to the value of the Compression tag found in the source file.

LZW compression can be specified together with a predictor value. A predictor value of 2 causes each scanline of the output image to undergo horizontal differencing before it is encoded; a value of 1 forces each scanline to be encoded without differencing. LZW-specific options are specified by appending a ``:''-separated list to the ``lzw'' option; e.g. "-c lzw:2" for LZW compression with horizontal differencing.

-C Specify the number of entries to use in the generated colormap. By default all 256 entries/colors are used.

-f Apply Floyd-Steinberg dithering before selecting a colormap entry.

-r Specify the number of rows (scanlines) in each strip of data written to the output file. By default, tiffmedian attempts to set the rows/strip that no more than 8 kilobytes of data appear in a strip.

This program is derived from Paul Heckbert's median program. pal2rgb (1), tiffinfo (1), tiffcp (1), tiffcmp (1), libtiff (3TIFF)

"Color Image Quantization for Frame Buffer Display", Paul Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.

Libtiff library home page: http://www.simplesystems.org/libtiff/