1Pamtopnm User Manual(0) Pamtopnm User Manual(0)
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6 pamtopnm - convert PAM image to PBM, PGM, or PPM
7
10 pamtopnm
11 [-assume]
13 [pnmfile]
15 Minimum unique abbreviation of option is acceptable. You may use dou‐
17 ble hyphens instead of single hyphen to denote options. You may use
18 white space in place of the equals sign to separate an option name from
19 its value.
20
23 This program is part of Netpbm(1).
24 pamtopnm reads a PAM image as input and produces an equivalent PBM,
26 PGM, or PPM (i.e. PNM) image, whichever is most appropriate, as output.
27 pamtopnm assumes the PAM image represents the information required for
29 a PBM, PGM, or PPM image if its tuple type is "BLACKANDWHITE",
30 "GRAYSCALE", or "RGB" and its depth and maxval are appropriate. If
31 this is not the case, pamtopnm fails.
32 However, you can override the tuple type requirement with the -assume
34 option.
35 pamtopnm produces a PPM image if the input PAM has depth 3 or 4; it
37 produces PGM or PBM if the input PAM has depth 1 or 2. Whether it pro‐
38 duced PGM or PBM depends upon the maxval: PBM for 1, PGM for anything
39 higher. The tuple type does not play a role in determining the output
40 type. You can use Netpbm programs such as pgmtopgm to generate a dif‐
41 ferent PNM output, but remember that Netpbm program that expects PGM
42 input will take PBM and so on.
43 Note that it's possible for an image which is formally color to in fact
45 contain only shades of gray and for an image which is formally
46 grayscale to contain only black and white. This program pays no atten‐
47 tion to that; an RGB input image produces a PPM output image even if
48 all the pixels are gray. But you can use ppmtopgm to convert a PPM
49 that you know is grayscale to the equivalent PGM, and you can use
50 pamthreshold to convert a PGM image you know is black and white to a
51 black and white PAM image and then use pamtopnm to convert that to PBM.
52 As with any Netpbm program that reads PAM images, pamtopnm also reads
55 PNM images as if they were PAM. In that case, pamtopnm's functions
56 reduces to simply copying the input to the output. But this can be
57 useful in a program that doesn't know whether its input is PAM or PNM
58 but needs to feed it to a program that only recognizes PNM.
59
62 In addition to the options common to all programs based on libnetpbm
63 (most notably -quiet, see
64 Common Options ⟨index.html#commonoptions⟩ ), pamtopnm recognizes the
65 following command line option:
66 -assume
70 When you specify -assume, you tell pamtopnm that you personally
71 vouch for the fact that the tuples contain the same data as
72 belongs in the channels of a PBM, PGM, or PPM file. The depth
73 must still conform, though, so to truly force a conversion, you
74 may have to run the input through pamchannel first. But be
75 careful with -assume. When you -assume, you make an -ass of u
76 and me.
77
82 pbmtopgm(1), pamditherbw(1), pgmtoppm(1), ppmtopgm(1), pamthreshold(1),
83 pam(1), pnm(1), pbm(1), pgm(1), ppm(1)
84
88 pamtopnm was new, along with the PAM format, in Netpbm 9.7 (August
89 2000).
90
92 This manual page was generated by the Netpbm tool 'makeman' from HTML
93 source. The master documentation is at
94 http://netpbm.sourceforge.net/doc/pamtopnm.html
96netpbm documentation 02 February 2018 Pamtopnm User Manual(0)