man > pamtopnm(1)

Pamtopnm User Manual(1)                General Commands Manual               Pamtopnm User Manual(1)

NAME
       pamtopnm - convert PAM image to PBM, PGM, or PPM


SYNOPSIS
       pamtopnm

       [-assume]

       [pnmfile]

       Minimum  unique  abbreviation of option is acceptable.  You may use double hyphens instead of
       single hyphen to denote options.  You may use white space in place of the equals sign to sep‐
       arate an option name from its value.


DESCRIPTION
       This program is part of Netpbm(1).

       pamtopnm reads a PAM image as input and produces an equivalent PBM, PGM, or  PPM  (i.e.  PNM)
       image, whichever is most appropriate, as output.

       pamtopnm assumes the PAM image represents the information required for a PBM, PGM, or PPM im‐
       age  if its tuple type is "BLACKANDWHITE", "GRAYSCALE", or "RGB" and its depth and maxval are
       appropriate.  If this is not the case, pamtopnm fails.

       However, you can override the tuple type requirement with the -assume option.

       pamtopnm produces a PPM image if the input PAM has depth 3 or 4; it produces PGM  or  PBM  if
       the  input PAM has depth 1 or 2.  Whether it produced PGM or PBM depends upon the maxval: PBM
       for 1, PGM for anything higher.  The tuple type does not play a role in determining the  out‐
       put  type.   You can use Netpbm programs such as pgmtopgm to generate a different PNM output,
       but remember that Netpbm program that expects PGM input will take PBM and so on.

       Note that it's possible for an image which is formally color to in fact contain  only  shades
       of  gray  and for an image which is formally grayscale to contain only black and white.  This
       program pays no attention to that; an RGB input image produces a PPM output image even if all
       the pixels are gray.  But you can use ppmtopgm to convert a PPM that you know is grayscale to
       the equivalent PGM, and you can use pamthreshold to convert a PGM image you know is black and
       white to a black and white PAM image and then use pamtopnm to convert that to PBM.


       As with any Netpbm program that reads PAM images, pamtopnm also reads PNM images as  if  they
       were PAM.  In that case, pamtopnm's functions reduces to simply copying the input to the out‐
       put.   But  this can be useful in a program that doesn't know whether its input is PAM or PNM
       but needs to feed it to a program that only recognizes PNM.


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



       -assume
              When  you  specify  -assume,  you tell pamtopnm that you personally vouch for the fact
              that the tuples contain the same data as belongs in the channels of a PBM, PGM, or PPM
              file.  The depth must still conform, though, so to truly force a conversion,  you  may
              have  to  run  the input through pamchannel first.  But be careful with -assume.  When
              you -assume, you make an -ass of u and me.




SEE ALSO
       pbmtopgm(1),  pamditherbw(1),  pgmtoppm(1),  ppmtopgm(1),  pamthreshold(1),  pam(1),  pnm(1),
       pbm(1), pgm(1), ppm(1)



HISTORY
       pamtopnm was new, along with the PAM format, in Netpbm 9.7 (August 2000).

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/pamtopnm.html

netpbm documentation                      02 February 2018                   Pamtopnm User Manual(1)