.TL
Pamfunc User Manual
.SH 1
pamfunc
.LP
Updated: June 2002
.br
Table Of Contents
.SH 2
NAME
.LP
pamfunc - Apply simple arithmetic functions to a Netpbm image
.SH 2
SYNOPSIS
.LP
\fBpamfunc\fR
{
\fB-multiplier=\fR\fIrealnum\fR |
\fB-divisor=\fR\fIrealnum\fR |
\fB-adder=\fR\fIinteger\fR |
\fB-subtractor=\fR\fIinteger\fR |
\fB-min=\fR\fIwholenum\fR |
\fB-max=\fR\fIwholenum\fR
}
[\fIfilespec\fR]
.LP
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.
.SH 2
DESCRIPTION
.LP
.LP
This program is part of Netpbm.
.LP
\fBpamfunc\fR reads a Netpbm image as input and produces a Netpbm
image as output, with the same format, maxval, and dimensions as the
input.  \fBpamfunc\fR applies a simple transfer function to each
sample in the input to generate the corresponding sample in the
output.  The options determine what function.
.LP
\fBpamarith\fR 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.
.SH 2
OPTIONS
.LP
.RS
.IP "\fB-multiplier=\fIrealnum\fB\fR"
.LP
This option makes the transfer function that of multiplying by
\fIrealnum\fR.  \fIrealnum\fR must be nonnegative.  If the result
is greater than the image maxval, it is clipped to the maxval.
.LP
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 \fBppmbrighten\fR and
\fBppmflash\fR
.LP
Also, see \fBppmdim\fR, which does the
same thing as \fBpamfunc -multiplier\fR on a PPM image with a
multiplier between 0 and 1,
except it uses integer arithmetic, so it may be faster.
.LP
And \fBppmfade\fR can generate a whole
sequence of images of brightness declining to black or increasing to
white, if that's what you want.
.IP "\fB-divisor=\fIrealnum\fB\fR"
.LP
This option makes the transfer function that of dividing by
\fIrealnum\fR.  \fIrealnum\fR must be nonnegative.  If the result
is greater than the image maxval, it is clipped to the maxval.
.LP
This is the same function as you would get with \fB-multiplier\fR,
specifying the multiplicative inverse of \fIrealnum\fR.
.IP "\fB-adder=\fIinteger\fB\fR"
.LP
This option makes the transfer function that of adding
\fIwholenum\fR.  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.
.LP
Note that in mathematics, this entity is called an "addend,"
and an "adder" is a snake.  We use "adder" because
it makes more sense.
.IP "\fB-subtractor=\fIinteger\fB\fR"
.LP
This option makes the transfer function that of subtracting
\fIwholenum\fR.  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.
.LP
Note that in mathematics, this entity is called a
"subtrahend" rather than a "subtractor."  We
use "subtractor" because it makes more sense.
.LP
This is the same function as you would get with \fB-multiplier\fR,
specifying the negative of \fIinteger\fR.
.IP "\fB-min=\fIwholenum\fB\fR"
.LP
This option makes the transfer function that of taking the
maximum of the argument and \fIwholenum\fR.  I.e the minimum
value in the output will be \fIwholenum\fR.
If \fIwholenum\fR is greater than the maxval, though, every sample
in the output will be maxval.
.IP "\fB-max=\fIwholenum\fB\fR"
.LP
This option makes the transfer function that of taking the
minimum of the argument and \fIwholenum\fR.  I.e the maximum
value in the output will be \fIwholenum\fR.
If \fIwholenum\fR is greater than the maxval, the function is
idempotent -- the output is identical to the input.
.RE
.SH 2
SEE ALSO
.LP
\fBppmdim\fR,
\fBppmbrighten\fR,
\fBpamdepth\fR,
\fBpamarith\fR,
\fBpamsummcol\fR,
\fBpamsumm\fR,
\fBppmfade\fR,
\fBpam\fR,
\fBpnm\fR,
.SH 2
HISTORY
.LP
.LP
This program was added to Netpbm in Release 10.3 (June 2002).
.br
\l'5i'
.SH 2
Table Of Contents
.LP
.IP \(bu
NAME
.IP \(bu
SYNOPSIS
.IP \(bu
DESCRIPTION
.IP \(bu
OPTIONS
.IP \(bu
SEE ALSO
.IP \(bu
HISTORY
.LP