xenial (1) pngnq.1.gz

Provided by: pngnq_1.0-2.2_amd64 bug

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 overwriting 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)