pamfunc



Pamfunc User Manual(0)                                  Pamfunc User Manual(0)




NAME

       pamfunc - Apply simple arithmetic functions to a Netpbm image



SYNOPSIS

       pamfunc  {  -multiplier=realnum  |  -divisor=realnum | -adder=integer |
       -subtractor=integer | -min=wholenum | -max=wholenum } [filespec]

       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).

       pamfunc reads a Netpbm image as input and produces a  Netpbm  image  as
       output,  with  the  same  format,  maxval, and dimensions as the input.
       pamfunc applies a simple transfer function to each sample in the  input
       to generate the corresponding sample in the output.  The options deter-
       mine what function.

       pamarith is the same thing, except only  for  PNM  images,  for  binary
       functions  --  it takes two PNM images as input and applies a specified
       simple arithmetic function (e.g. addition) on pairs of samples from the
       two to produce the single output image.




OPTIONS

       -multiplier=realnum

              This option makes the transfer function that of multiplying by
                   realnum.  realnum must be nonnegative.  If the result
                   is greater than the image maxval, it is clipped to the max-
              val.

              Where the input is a PGM or PPM image, this has the effect of
                   dimming or brightening it.  For a different kind of bright-
              ening,
                   see ppmbrighten(1)and ppmflash(1)

              Also, see ppmdim(1),whichdoesthe
                   same thing as pamfunc -multiplier on a PPM image with a
                   multiplier between 0 and 1,
                   except it uses integer arithmetic, so it may be faster.

              And ppmfade(1)cangenerateawhole
                   sequence  of  images  of  brightness  declining to black or
              increasing to
                   white, if that’s what you want.


       -divisor=realnum

              This option makes the transfer function that of dividing by
                   realnum.  realnum must be nonnegative.  If the result
                   is greater than the image maxval, it is clipped to the max-
              val.

              This is the same function as you would get with -multiplier,
                   specifying the multiplicative inverse of realnum.


       -adder=integer

              This option makes the transfer function that of adding
                   wholenum.  If the result is greater than the image maxval,
                   it  is  clipped to the maxval.  If it is less than zero, it
              is
                   clipped to zero.

              Note that in mathematics, this entity is called an ’addend,’
                   and an ’adder’ is a snake.  We use ’adder’ because
                   it makes more sense.


       -subtractor=integer

              This option makes the transfer function that of subtracting
                   wholenum.  If the result is greater than the image maxval,
                   it is clipped to the maxval.  If it is less than  zero,  it
              is
                   clipped to zero.

              Note that in mathematics, this entity is called a
                   ’subtrahend’ rather than a ’subtractor.’  We
                   use ’subtractor’ because it makes more sense.

              This is the same function as you would get with -multiplier,
                   specifying the negative of integer.


       -min=wholenum

              This option makes the transfer function that of taking the
                   maximum of the argument and wholenum.  I.e the minimum
                   value in the output will be wholenum.

                   If  wholenum is greater than the maxval, though, every sam-
              ple
                   in the output will be maxval.


       -max=wholenum

              This option makes the transfer function that of taking the
                   minimum of the argument and wholenum.  I.e the maximum
                   value in the output will be wholenum.

                   If wholenum is greater than the maxval, the function is
                   idempotent -- the output is identical to the input.





SEE ALSO

       ppmdim(1),  ppmbrighten(1),  pnmdepth(1),  pamarith(1),  pamsummcol(1),
       pamsumm(1), ppmfade(1), pam(1), pnm(1),



HISTORY

       This program was added to Netpbm in Release 10.3 (June 2002).



netpbm documentation               June 2002            Pamfunc User Manual(0)

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