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.remotesensing.org/libtiff/