NAME

       pamunlookup - inverse of pamlookup

SYNOPSIS

       pamunlookup -lookupfile=lookupfile inputfile

       All  options  can be abbreviated to their shortest unique prefix.  You may use two hyphens
       instead of one.  You may separate an option name and its value with white space instead of
       an equals sign.

DESCRIPTION

       This program is part of Netpbm(1).

       pamunlookup  is  best  described  as  the  inverse  of  pamlookup (without -byplane).  For
       example, the following normally yields output identical the input:

           $ cat input.ppm | \
               pamunlookup -lookupfile=map.pam | \
               pamlookup -lookupfile=map.pam \
               > output.ppm

       Specifically, pamunlookup takes an input image and produces an output image  of  the  same
       width  and  height  in which each tuple is a single number.  That number is the index in a
       given lookup table of the tuple value that is in the same position in the input image.

       You specify the lookup table the same way as for pamlookup ⟨pamlookup.html#lookupimage⟩ .

       Where a tuple in the input image is not in the lookup table, the number pamunlookup places
       in  the  output  index  image  is  one greater than the highest index in the lookup table.
       Accordingly, the maxval of the output index image is the size of the lookup table.

   Example
       Here is an example of pamunlookup's function.

       Consider an input image consisting of a 3x2 PPM as follows:

       red     yellow   red
       beige   beige    beige

       and a lookup table consisting of a 3x1 PPM image as follows:

       red   yellow   beige

       The lookup table above says Index 0 corresponds to the color red, Index 1  corresponds  to
       yellow,  and  Index  2  corresponds  to beige.  The output of pamunlookup is the following
       index image:

       0   1   0
       2   2   2

   Miscellaneous
       The inputfile argument identifies the file containing the index PAM or PNM image.  - means
       Standard  Input.   It  won't  work  if both the input image file and lookup table file are
       Standard Input.

       The output index image goes to Standard Output.

OPTIONS

       In addition to the options common to all programs based on libnetpbm (most notably -quiet,
       see
        Common Options ⟨index.html#commonoptions⟩ ), pamunlookup recognizes the following command
       line option:

       -lookupfile=lookupfile
              lookupfile names the file that contains the PAM or PNM image  that  is  the  lookup
              table.  This option is mandatory.

SEE ALSO

       pamlookup(1), ppmchange(1), pnmcolormap(1), pnm(1), pam(1)

HISTORY

       pamunlookup was new in Netpbm 10.72 (September 2015).

DOCUMENT SOURCE

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

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