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# tools/unsupported/CMakeLists.txt
# tools/unsupported/tif_tools-unsupported_versioninfo.rc
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tiffmedian
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==========
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.. program:: tiffmedian
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Synopsis
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--------
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**tiffmedian** [ *options* ] *input.tif* *output.tif*
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Description
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-----------
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:program:`tiffmedian` applies the median cut algorithm to an RGB
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image in *input.tif* to generate a palette image that is written to
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*output.tif*. The generated colormap has, by default, 256 entries.
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The image data is quantized by mapping each pixel to the closest color
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values in the colormap.
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Options
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-------
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.. option:: -c
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Specify the compression to use for data written to the output file:
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:command:`-c none` for no compression,
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:command:`-c packbits` for PackBits compression,
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:command:`-c lzw` for Lempel-Ziv & Welch compression,
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:command:`-c zip` for Deflate compression.
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By default :program:`tiffmedian` will compress data according to the
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value of the ``Compression`` tag found in the source file.
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LZW compression can be specified together with a ``predictor`` value.
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A predictor value of 2 causes each scanline of the output image to
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undergo horizontal differencing before it is encoded; a value of 1
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forces each scanline to be encoded without differencing.
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LZW-specific options are specified by appending a ``:``-separated
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list to the ``lzw`` option; e.g. ``-c lzw:2`` for LZW compression
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with horizontal differencing.
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.. option:: -C
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Specify the number of entries to use in the generated colormap.
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By default all 256 entries/colors are used.
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.. option:: -f
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Apply Floyd-Steinberg dithering before selecting a colormap entry.
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.. option:: -r
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Specify the number of rows (scanlines) in each strip of data
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written to the output file. By default, :program:`tiffmedian`
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attempts to set the rows/strip that no more than 8 kilobytes of
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data appear in a strip.
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Notes
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-----
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This program is derived from Paul Heckbert's :program:`median` program.
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See also
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--------
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:doc:`pal2rgb` (1),
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:doc:`tiffinfo` (1),
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:doc:`tiffcp` (1),
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:doc:`tiffcmp` (1),
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:doc:`/functions/libtiff` (3tiff),
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**"Color Image Quantization for Frame Buffer Display"**,
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Paul Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.
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