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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 ex-
     tended 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 val-
	    ues sample less of the image pixels and thus are faster but less ac-
	    curate. 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 Stein-
	    berg 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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<https://man.freebsd.org/cgi/man.cgi?query=pngnq&sektion=1&manpath=FreeBSD+Ports+15.1.quarterly>

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