TIFFMEDIAN(1) User Commands TIFFMEDIAN(1)

NAME

tiffmedian - apply the median cut algorithm to data in a TIFF file

SYNOPSIS

tiffmedian [ options ] input.tif output.tif

DESCRIPTION

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.

OPTIONS

-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.

NOTES

This program is derived from Paul Heckbert's median program.

SEE ALSO

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/

libtiff November 2, 2005 TIFFMEDIAN(1)