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: