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2PNGNQ(1)                         User Manuals                         PNGNQ(1)
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NAME

7       pngnq - quantize png images
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SYNOPSIS

10       pngnq  [-vfhV][-s  sample_factor  ][-Q dither ][-g gamma ][-e extension
11       ][-d dir ][-n colors ][ inputfiles ]
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DESCRIPTION

14       pngnq Quantizes a 32-bit RGBA PNG image to an 8 bit  RGBA  palette  PNG
15       using  the  neuquant  algorithm. The output file name is the input file
16       name extended with "-nq8.png" or a specified extension.
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OPTIONS

20       -v     Verbose mode. Prints status messages.
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22       -f     Force ovewriting of files.
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24       -s sample factor
25              Sample factor. The neuquant algorithm samples pixels stepping by
26              this  value.   The default value of 3 gives good results. Higher
27              values sample less of the image pixels and thus are  faster  but
28              less accurate. A factor of 1 samples every image pixel.
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30       -n colors
31              Specifies  the  number of colors to quantize to. Defaults to 256
32              which is the maximum.  The minimum here is 2.
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34       -Q dither
35              Choose a dithering method: n = no dither (default),  f  =  Floyd
36              Steinberg dithering.
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38       -g gamma
39              Set  the  image  gamma  correction. If not present, uses the png
40              file's gamma or defaults to 1.0.
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42       -e extension
43              Specifies the new filename extension.  Defaults  to  "-nq8.png".
44              Pngnq  drops  .png  from  the original filenames. If you set the
45              argument of the -e option to .png and choose the -f  option  the
46              input file will be overwritten.
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48       -d dir Tells  pngnq  to  put output files in a directory other than the
49              one the input files are in.
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51       input files
52              The png files to be processed. Defaults to standard input if not
53              specified.   If  standard input is being processed the output is
54              sent to standard output.
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56       -h     Print program help.
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58       -V     Print version number and library versions.
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BUGS

62       Does not deal correctly  with  greyscale  alpha  images  with  low  bit
63       depths, but these wont benefit from quantizing.
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AUTHOR

67       Stuart Coyle <stuart.coyle@gmail.com>
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SEE ALSO

70       png(5)
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74Linux                              MAY 2009                           PNGNQ(1)
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