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<H1>pamfunc</H1>
Updated: July 2007
<BR>
<A HREF="#index">Table Of Contents</A>
<H2>NAME</H2>
pamfunc - Apply a simple monadic arithmetic function to a Netpbm image
<H2 id="synopsis">SYNOPSIS</H2>
<B>pamfunc</B>
{
<b>-multiplier=</b><i>realnum</i> |
<b>-divisor=</b><i>realnum</i> |
<b>-adder=</b><i>integer</i> |
<b>-subtractor=</b><i>integer</i> |
<b>-min=</b><i>wholenum</i> |
<b>-max=</b><i>wholenum</i>
<b>-andmask=</b><i>hexmask</i>
<b>-ormask=</b><i>hexmask</i>
<b>-xormask=</b><i>hexmask</i>
<b>-not</b>
<b>-shiftleft=</b><i>count</i>
<b>-shiftright=</b><i>count</i>
}
[<I>filespec</I>]
<P>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.
<H2 id="description">DESCRIPTION</H2>
<p>This program is part of <a href="index.html">Netpbm</a>.
<P><b>pamfunc</b> reads a Netpbm image as input and produces a Netpbm
image as output, with the same format, maxval, and dimensions as the
input. <b>pamfunc</b> applies a simple transfer function to each
sample in the input to generate the corresponding sample in the
output. The options determine what function.
<P><b>pamarith</b> is the same thing for binary functions -- it takes
two 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.
<H2 id="options">OPTIONS</H2>
<DL COMPACT>
<DT><B>-multiplier=<i>realnum</i></B>
<DD>
<P>This option makes the transfer function that of multiplying by
<i>realnum</i>. <i>realnum</i> must be nonnegative. If the result
is greater than the image maxval, it is clipped to the maxval.
<P>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 <a href="ppmbrighten.html"><b>ppmbrighten</b></a> and
<a href="ppmflash.html"><b>ppmflash</b></a>
<P>Also, see <a href="ppmdim.html"><b>ppmdim</b></a>, which does the
same thing as <b>pamfunc -multiplier</b> on a PPM image with a
multiplier between 0 and 1,
except it uses integer arithmetic, so it may be faster.
<P>And <a href="ppmfade.html"><b>ppmfade</b></a> can generate a whole
sequence of images of brightness declining to black or increasing to
white, if that's what you want.
<DT><B>-divisor=<i>realnum</i></B>
<DD>
<P>This option makes the transfer function that of dividing by
<i>realnum</i>. <i>realnum</i> must be nonnegative. If the result
is greater than the image maxval, it is clipped to the maxval.
<P>This is the same function as you would get with <b>-multiplier</b>,
specifying the multiplicative inverse of <i>realnum</i>.
<DT><B>-adder=<i>integer</i></B>
<DD>
<P>This option makes the transfer function that of adding
<i>wholenum</i>. 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.
<p>Note that in mathematics, this entity is called an "addend,"
and an "adder" is a snake. We use "adder" because
it makes more sense.
<DT><B>-subtractor=<i>integer</i></B>
<DD>
<P>This option makes the transfer function that of subtracting
<i>wholenum</i>. 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.
<p>Note that in mathematics, this entity is called a
"subtrahend" rather than a "subtractor." We
use "subtractor" because it makes more sense.
<P>This is the same function as you would get with <b>-adder</b>,
specifying the negative of <i>integer</i>.
<DT><B>-min=<i>wholenum</i></B>
<DD>
<P>This option makes the transfer function that of taking the
maximum of the argument and <i>wholenum</i>. I.e the minimum
value in the output will be <i>wholenum</i>.
If <i>wholenum</i> is greater than the maxval, though, every sample
in the output will be maxval.
<DT><B>-max=<i>wholenum</i></B>
<DD>
<P>This option makes the transfer function that of taking the
minimum of the argument and <i>wholenum</i>. I.e the maximum
value in the output will be <i>wholenum</i>.
If <i>wholenum</i> is greater than the maxval, the function is
idempotent -- the output is identical to the input.
<DT><B>-andmask=<i>hexmask</i></B>
<DD>
<P>This option makes the transfer function that of bitwise anding
with <i>hexmask</i>.
<p><i>hexmask</i> is in hexadecimal. Example: <kbd>0f</kbd>
<p>See section <a href="#maxval">Maxval</a> for the special
meaning of maxval with respect to bit string operations such as
this.
<p>This option was new in Netpbm 10.40 (September 2007).
<DT><B>-ormask=<i>hexmask</i></B>
<DD>
<P>This option makes the transfer function that of bitwise
inclusive oring with <i>hexmask</i>.
<p>This is analogous to <b>-andmask</b>.
<p>This option was new in Netpbm 10.40 (September 2007).
<DT><B>-xormask=<i>hexmask</i></B>
<DD>
<P>This option makes the transfer function that of bitwise
exclusive oring with <i>hexmask</i>.
<p>This is analogous to <b>-andmask</b>.
<p>This option was new in Netpbm 10.40 (September 2007).
<dt><b>-not</b>
<dd>
<p>This option makes the transfer function that of bitwise logical
inversion (e.g. sample value 0xAA becomes 0x55).
<p>See section <a href="#maxval">Maxval</a> for the special
meaning of maxval with respect to bit string operations such as
this.
<p><b>pnminvert</b> does the same thing for a bilevel visual image
which has maxval 1 or is of PBM type.
<p>This option was new in Netpbm 10.40 (September 2007).
<DT><B>-shiftleft=<i>count</i></B>
<DD>
<P>This option makes the transfer function that of bitwise shifting
left by <i>count</i> bits.
<p>See section <a href="#maxval">Maxval</a> for the special
meaning of maxval with respect to bit string operations such as
this.
<p>This option was new in Netpbm 10.40 (September 2007).
<DT><B>-shiftright=<i>count</i></B>
<DD>
<P>This option makes the transfer function that of bitwise shifting
right by <i>count</i> bits.
<p>This is analogous to <b>-shiftleft</b>.
<p>This option was new in Netpbm 10.40 (September 2007).
</DL>
<h2 id="maxval">MAXVAL</h2>
<p>For the arithmetic functions, the maxval has no meaning. The function
applies to the sample value as an integer. (Note that this differs from
the usual interpretation of PAM samples as being a fraction of a maxval,
but <em>does</em> produce more intuitive result: 2 times 5 is 10.
<P>But with the bit string operations, the maxval has a special
meaning. The functions in question are: <B>-andmask</B>, <B>-ormask</B>,
<B>-xormask</B>, <B>-not</B>, <b>-shiftleft</b>, and <b>-shiftright</b>.
<p>With these, each sample value the input image, and in the output
image, represents a bit string, not a number. The maxval tells how
wide the bit string is. The maxval must be a full binary count (a
power of two minus one, such as 0xff) and the number of ones in it is
the width of the bit string.
<p>For a masking function, the mask value you specify must not have
more significant bits than the width indicated by the maxval.
<p>For a shifting operation, the shift count you specify must not be
greater than the width indicated by the maxval.
<p>The maxval of the output image is the same as that of the input image.
<H2 id="seealso">SEE ALSO</H2>
<B><A HREF="ppmdim.html">ppmdim</A></B>,
<B><A HREF="ppmbrighten.html">ppmbrighten</A></B>,
<B><A HREF="pamdepth.html">pamdepth</A></B>,
<B><A HREF="pamarith.html">pamarith</A></B>,
<b><A HREF="pamsummcol.html">pamsummcol</A></b>,
<b><A HREF="pamsumm.html">pamsumm</A></b>,
<B><A HREF="ppmfade.html">ppmfade</A></B>,
<B><A HREF="pnminvert.html">pnminvert</A></B>,
<B><A HREF="pam.html">pam</A></B>,
<B><A HREF="pnm.html">pnm</A></B>,
<H2 id="history">HISTORY</H2>
<p>This program was added to Netpbm in Release 10.3 (June 2002).
<HR>
<A NAME="index"> </A>
<H2>Table Of Contents</H2>
<UL>
<LI><A HREF="#synopsis">SYNOPSIS</A>
<LI><A HREF="#description">DESCRIPTION</A>
<LI><A HREF="#options">OPTIONS</A>
<LI><A HREF="#maxval">MAXVAL</A>
<LI><A HREF="#seealso">SEE ALSO</A>
<LI><A HREF="#history">HISTORY</A>
</UL>
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