src/tiff/man/tiffmedian.1

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  24 .if n .po 0
  25 .TH TIFFMEDIAN 1 "November 2, 2005" "libtiff"
  26 .SH NAME
  27 tiffmedian \- apply the median cut algorithm to data in a
  28 .SM TIFF
  29 file
  30 .SH SYNOPSIS
  31 .B tiffmedian
  32 [
  33 .I options
  34 ]
  35 .I input.tif
  36 .I output.tif
  37 .SH DESCRIPTION
  38 .I tiffmedian
  39 applies the median cut algorithm to an
  40 .SM RGB
  41 image in
  42 .I input.tif
  43 to generate a palette image that is written to
  44 .IR output.tif .
  45 The generated colormap has, by default, 256 entries.
  46 The image data is quantized by mapping each
  47 pixel to the closest color values in the colormap.
  48 .SH OPTIONS
  49 .TP
  50 .B \-c
  51 Specify the compression to use for data written to the output file:
  52 .B none
  53 for no compression,
  54 .B packbits
  55 for PackBits compression,
  56 .B lzw
  57 for Lempel-Ziv & Welch compression,
  58 and
  59 .B zip
  60 for Deflate compression.
  61 By default
  62 .I tiffmedian
  63 will compress data according to the value of the
  64 .I Compression
  65 tag found in the source file.
  66 .IP
  67 .SM LZW
  68 compression can be specified together with a
  69 .I predictor
  70 value.
  71 A predictor value of 2 causes
  72 each scanline of the output image to undergo horizontal
  73 differencing before it is encoded; a value
  74 of 1 forces each scanline to be encoded without differencing.
  75 LZW-specific options are specified by appending a ``:''-separated
  76 list to the ``lzw'' option; e.g.
  77 .B "\-c lzw:2"
  78 for
  79 .SM LZW
  80 compression with horizontal differencing.
  81 .TP
  82 .B \-C
  83 Specify the number of entries to use in the generated colormap.
  84 By default all 256 entries/colors are used.
  85 .TP
  86 .B \-f
  87 Apply Floyd-Steinberg dithering before selecting a colormap entry.
  88 .TP
  89 .B \-r
  90 Specify the number of rows (scanlines) in each strip of data
  91 written to the output file.
  92 By default,
  93 .I tiffmedian
  94 attempts to set the rows/strip
  95 that no more than 8 kilobytes of data appear in a strip.
  96 .SH NOTES
  97 This program is derived from Paul Heckbert's
  98 .I median
  99 program.
 100 .SH "SEE ALSO"
 101 .BR pal2rgb (1),
 102 .BR tiffinfo (1),
 103 .BR tiffcp (1),
 104 .BR tiffcmp (1),
 105 .BR libtiff (3TIFF)
 106 .PP
 107 .BR "Color Image Quantization for Frame Buffer Display",
 108 Paul Heckbert, SIGGRAPH proceedings, 1982, pp. 297-307.
 109 .PP
 110 Libtiff library home page:
 111 .BR http://www.remotesensing.org/libtiff/