1Pnmquant User Manual(0)                                Pnmquant User Manual(0)
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NAME

6       pnmquant - quantize the colors in a Netpbm image to a smaller set
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SYNOPSIS

10       pnmquant  [-center|-meancolor|-meanpixel] [-floyd|-fs] [-nofloyd|-nofs]
11       [-spreadbrightness|-spreadluminosity]     {[-norandom]|[-randomseed=n]}
12       ncolors [pnmfile]
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14       All  options  can  be abbreviated to their shortest unique prefix.  You
15       may use two hyphens instead of one to designate an option.  You may use
16       either  white  space  or  equals  signs  between an option name and its
17       value.
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DESCRIPTION

22       This program is part of Netpbm(1).
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24       pnmquant reads a PNM image as input.  It chooses ncolors colors to best
25       represent  the  image,  maps  the  existing colors to the new ones, and
26       writes a PNM image as output.
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28       This program is simply a combination of pnmcolormap and pnmremap, where
29       the  colors of the input are remapped using a color map which is gener‐
30       ated from the colors in that same input.  The  options  have  the  same
31       meaning  as  in  those programs.  See their documentation to understand
32       pnmquant.
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34       You may actually get fewer than ncolors colors in the output because
35         the method pnmcolormap uses to choose the best set of colors for the
36         image is not the same as the method pnmremap uses to determine the
37         best color from the set to represent an individual color.  For  exam‐
38       ple,
39         pnmcolormap may include salmon in the color map as the best
40         representative  of a pink pixel in the input and include coral in the
41       color
42         map as the best representative of an actual coral pixel in the input.
43       But
44         pnmremap is free to use any color in the color map to represent that
45         pink  pixel  and  would  find  coral  is a closer match for pink than
46       salmon and
47         therefore use coral for pink.  pnmremap might not use salmon
48         for any pixel.
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50       This waste of a slot in the color map is a consequence of the  approxi‐
51       mate
52         method pnmcolormap uses in order to compute the color map with a
53         practical amount of computation.
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57   Running pnmcolormap and pnmremap Separately
58       It is much faster to call pnmcolormap and pnmremap directly than to run
59       pnmquant.  You save the overhead of the Perl interpreter  and  creating
60       two extra processes.  pnmquant is just a convenience.
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62       Here is an example of the relationship between the programs:
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64       This:
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66           $ pnmquant 256 myimage.pnm >/tmp/colormap.pnm >myimage256.pnm
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68       does essentially this:
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70           $ pnmcolormap 256 myimage.pnm >/tmp/colormap.pnm
71           $ pnmremap -mapfile=/tmp/colormap.pnm myimage.pnm >myimage256.pnm
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OPTIONS

75       In  addition  to  the options common to all programs based on libnetpbm
76       (most notably -quiet, see
77        Common Options ⟨index.html#commonoptions⟩ ), pnmquant  recognizes  the
78       following command line options:
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81   Options Passed to pnmcolormap
82       These  options  control the selection of the palette.  They are options
83       to pnmcolormap(1).
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87       -center
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89       -meancolor
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91       -meanpixel
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93       -spreadbrightness
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95       -spreadluminosity
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99   Options Passed to pnmremap
100       These options control which color from the palette the program uses to
101         replace a pixel of a certain color from the input.  They are  options
102       to pnmremap(1).
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106       -floyd
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108       -fs
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110       -nofloyd
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112       -nofs
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114       -norandom
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116       -randomseed
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118       -norandom
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HISTORY

123       pnmquant did not exist before Netpbm 9.21 (January 2001).  Before that,
124       ppmquant did the same thing, but only on PPM images.  ppmquant  contin‐
125       ues  to  exist,  but  is  only  a front end (for name compatibility) to
126       pnmquant.
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128       -version did not exist before Netpbm 10.75 (June 2016).
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131       -norandom did not exist before Netpbm 10.82 (March 2018).
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SEE ALSO

135       pnmcolormap(1), pnmremap(1), ppmquantall(1), pamdepth(1), ppmdither(1),
136       ppmquant(1), pnm(1)
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DOCUMENT SOURCE

139       This  manual  page was generated by the Netpbm tool 'makeman' from HTML
140       source.  The master documentation is at
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142              http://netpbm.sourceforge.net/doc/pnmquant.html
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144netpbm documentation           09 February 2019        Pnmquant User Manual(0)
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