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



Table Of Contents


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  gener-
       ate the corresponding sample in the output.  The options
       determine 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 maxval.

              Where  the  input is a PGM or PPM image, this has
              the effect of
                   dimming or brightening it.  For a  different
              kind of brightening,
                   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 maxval.

              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 sample
                   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),
       ppmfade(1), pbm(1), pbm(1),


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



netpbm documentation       June 2002     Pamfunc User Manual(0)
