pnmquant - Man Page

• Generate an image using only n_colors or less colors as close as possible to the input image: pnmquant n_colors path/to/input.pnm > path/to/output.pnm

tldr.sh

pnmquant [-center|-meancolor|-meanpixel] [-floyd|-fs] [-nofloyd|-nofs] [-spreadbrightness|-spreadluminosity] {[-norandom]|[-randomseed=n]} ncolors [pnmfile]

All options can be abbreviated to their shortest unique prefix.  You may use two hyphens instead of one to designate an option.  You may use either white space or equals signs between an option name and its value.

This program is part of Netpbm(1).

pnmquant reads a PNM image as input.  It chooses ncolors colors to best represent the image, maps the existing colors to the new ones, and writes a PNM image as output.

This program is simply a combination of pnmcolormap and pnmremap, where the colors of the input are remapped using a color map which is generated from the colors in that same input.  The options have the same meaning as in those programs.  See their documentation to understand pnmquant.

You may actually get fewer than ncolors colors in the output because
 the method pnmcolormap uses to choose the best set of colors for the
 image is not the same as the method pnmremap uses to determine the
 best color from the set to represent an individual color.  For example,
 pnmcolormap may include salmon in the color map as the best
 representative of a pink pixel in the input and include coral in the color
 map as the best representative of an actual coral pixel in the input.  But
 pnmremap is free to use any color in the color map to represent that
 pink pixel and would find coral is a closer match for pink than salmon and
 therefore use coral for pink.  pnmremap might not use salmon
 for any pixel.

This waste of a slot in the color map is a consequence of the approximate
 method pnmcolormap uses in order to compute the color map with a
 practical amount of computation.

    $ pnmquant 256 myimage.pnm >/tmp/colormap.pnm >myimage256.pnm

    $ pnmcolormap 256 myimage.pnm >/tmp/colormap.pnm
    $ pnmremap -mapfile=/tmp/colormap.pnm myimage.pnm >myimage256.pnm

In addition to the options common to all programs based on libnetpbm (most notably -quiet, see Common Options ), pnmquant recognizes the following command line options:

pnmquant did not exist before Netpbm 9.21 (January 2001). Before that, ppmquant did the same thing, but only on PPM images.  ppmquant continues to exist, but is only a front end (for name compatibility) to pnmquant.

-version did not exist before Netpbm 10.75 (June 2016).
 

-norandom did not exist before Netpbm 10.82 (March 2018).
 

pnmcolormap(1), pnmremap(1), pnmquantall(1), pamdepth(1), ppmdither(1), ppmquant(1), pnm(1)

This manual page was generated by the Netpbm tool 'makeman' from HTML source.  The master documentation is at

http://netpbm.sourceforge.net/doc/pnmquant.html

jpegtopnm(1), pambackground(1), pamdepth(1), pamtosvg(1), pamtotga(1), pnmcolormap(1), pnmindex(1), pnmquantall(1), pnmremap(1), pnmrotate(1), pnmshear(1), pnmtopalm(1), ppmcie(1), ppmdither(1), ppmforge(1), ppmpat(1), ppmquant(1), ppmtobmp(1), ppmtoleaf(1), ppmtomitsu(1).