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 dou-
ble hyphens instead of single hyphen to denote options. You may use
white space in place of the equals sign to separate 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 image 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 pro-
duced 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 output
type. You can use Netpbm programs such as pgmtopgm to generate a dif-
ferent 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 atten-
tion 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 re-
duces to simply copying the input to the output. But this can be use-
ful 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 ⟨index.html#commonoptions⟩ ), 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 be-
longs 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)
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