tiffmedian
apply the median cut algorithm to data in a TIFF file
see also :
pal2rgb - tiffinfo - tiffcp - tiffcmp
Synopsis
tiffmedian
[ options ] input.tif output.tif
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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 ,
tiffinfo , tiffcp , tiffcmp ,
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/