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tiffmedian - apply the median cut algorithm
to data in a TIFF
file
tiffmedian [ options ] input.tif output.tif
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.
- -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.
This program
is derived from Paul Heckbert’s median program.
pal2rgb(1)
, tiffinfo(1)
,
tiffcp(1)
, tiffcmp(1)
, libtiff(3)
"Color Image Quantization for Frame Buffer
Display", Paul Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.
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