.\" $Id: tiffmedian.1,v 1.3 2005-11-02 11:07:19 dron 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.

.\"

.if n .po 0

.TH TIFFMEDIAN 1 "November 2, 2005" "libtiff"

.SH NAME

tiffmedian \- apply the median cut algorithm to data in a

.SM TIFF

file

.SH SYNOPSIS

.B tiffmedian

[

.I options

]

.I input.tif

.I output.tif

.SH DESCRIPTION

.I tiffmedian

applies the median cut algorithm to an

.SM RGB

image in

.I input.tif

to generate a palette image that is written to

.IR 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.

.SH OPTIONS

.TP

.B \-c

Specify the compression to use for data written to the output file:

.B none 

for no compression,

.B packbits

for PackBits compression,

.B lzw

for Lempel-Ziv & Welch compression,

and

.B zip

for Deflate compression.

By default

.I tiffmedian

will compress data according to the value of the

.I Compression

tag found in the source file.

.IP

.SM LZW

compression can be specified together with a 

.I 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.

.B "\-c lzw:2"

for

.SM LZW

compression with horizontal differencing.

.TP

.B \-C

Specify the number of entries to use in the generated colormap.

By default all 256 entries/colors are used.

.TP

.B \-f

Apply Floyd-Steinberg dithering before selecting a colormap entry.

.TP

.B \-r

Specify the number of rows (scanlines) in each strip of data

written to the output file.

By default,

.I tiffmedian

attempts to set the rows/strip

that no more than 8 kilobytes of data appear in a strip.

.SH NOTES

This program is derived from Paul Heckbert's

.I median

program.

.SH "SEE ALSO"

.BR pal2rgb (1),

.BR tiffinfo (1),

.BR tiffcp (1),

.BR tiffcmp (1),

.BR libtiff (3TIFF)

.PP

.BR "Color Image Quantization for Frame Buffer Display",

Paul Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.

.PP

Libtiff library home page:

.BR http://www.remotesensing.org/libtiff/