Pamfunc User Manual(0) Pamfunc User Manual(0)NAMEpamfunc - Apply simple arithmetic functions to a Netpbm image
SYNOPSISpamfunc { -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 ALSOppmdim(1), ppmbrighten(1), pamdepth(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)
