TIFFMEDIAN(1) General Commands Manual 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 in-
put.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 col-
ormap.
OPTIONS
-c Specify the compression to use for data written to the output
file: none for no compression, packbits for PackBits compres-
sion, lzw for Lempel-Ziv & Welch compression, and zip for De-
flate compression. By default tiffmedian will compress data ac-
cording 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 out-
put image to undergo horizontal differencing before it is en-
coded; 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 en-
try.
-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, SIG-
GRAPH proceedings, 1982, pp. 297-307.
Libtiff library home page: http://www.simplesystems.org/libtiff/
libtiff November 2, 2005 TIFFMEDIAN(1)
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