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PNGNQ(1)			 User Manuals			      PNGNQ(1)

NAME
       pngnq - quantize png images

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

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

OPTIONS
       -v     Verbose mode. Prints status messages.

       -f     Force ovewriting of files.

       -s sample factor
	      Sample factor. The neuquant algorithm samples pixels stepping by
	      this  value.   The default value of 3 gives good results. Higher
	      values sample less of the image pixels and thus are  faster  but
	      less accurate. A factor of 1 samples every image pixel.

       -n colors
	      Specifies	 the  number of colors to quantize to. Defaults to 256
	      which is the maximum.  The minimum here is 2.

       -Q dither
	      Choose a dithering method: n = no dither (default),  f  =	 Floyd
	      Steinberg dithering.

       -g gamma
	      Set  the	image  gamma  correction. If not present, uses the png
	      file's gamma or defaults to 1.0.

       -e extension
	      Specifies the new filename extension.  Defaults  to  "-nq8.png".
	      Pngnq  drops  .png  from	the original filenames. If you set the
	      argument of the -e option to .png and choose the -f  option  the
	      input file will be overwritten.

       -d dir Tells  pngnq  to	put output files in a directory other than the
	      one the input files are in.

       input files
	      The png files to be processed. Defaults to standard input if not
	      specified.   If  standard input is being processed the output is
	      sent to standard output.

       -h     Print program help.

       -V     Print version number and library versions.

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

AUTHOR
       Stuart Coyle <stuart.coyle@gmail.com>

SEE ALSO
       png(5)

Linux				   MAY 2009			      PNGNQ(1)

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