pamtopnm - convert PAM image to PBM, PGM, or PPM
pamtopnm [-assume] [pnmfile]
All options may be abbreviated to the shortest unique prefix.
Reads a PAM image as input. 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.
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 output. 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.
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.
pbmtopgm(1), pgmtopbm(1), pgmtoppm(1), ppmtopgm(1), pam(5), pnm(5), pbm(5), pgm(5), ppm(5)
03 August 2000 pamtopnm(1)