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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.3//EN">
<html><head><title>Pamcut User Manual</title></head>
<body>
<h1>pamcut</h1>
Updated: 26 February 2024
<br>
<a href="#index">Table Of Contents</a>
<h2>NAME</h2>
pamcut - select a rectangular region of a PAM, PBM, PGM, or PPM image
<h2 id="synopsis">SYNOPSIS</h2>
<b>pamcut</b>
[<b>-left </b><i>colnum</i>]
[<b>-right </b><i>colnum</i>]
[<b>-top </b><i>rownum</i>]
[<b>-bottom </b><i>rownum</i>]
[<b>-width </b><i>cols</i>]
[<b>-height </b><i>rows</i>]
[<b>-pad</b>]
[<b>-cropleft </b><i>numcols</i>]
[<b>-cropright </b><i>numcols</i>]
[<b>-croptop </b><i>numrows</i>]
[<b>-cropbottom </b><i>numrows</i>]
[<b>-reportonly</b>]
[<b>-verbose</b>]
[<i>left</i> <i>top</i> <i>width</i> <i>height</i>]
[<i>pnmfile</i>]
<p>Minimum unique abbreviations of options are acceptable. You may use
double hyphens instead of single hyphen to denote options. You may use
white space in place of the equals sign to separate an option name
from its value.
<h2 id="description">DESCRIPTION</h2>
<p>This program is part of <a href="index.html">Netpbm</a>.
<p><b>pamcut</b> reads a PAM, PBM, PGM, or PPM image as input and
extracts the specified rectangle, and produces the same kind of image
as output.
<p>You can specify either the rectangle to cut out and keep or specify the
edges to crop off and discard, or a combination.
<p>To request edges be cropped off, use options <b>-cropleft</b>,
<b>-cropright</b>, <b>-croptop</b>, and <b>-cropbottom</b> to indicate how many
rows or columns to discard.
<p>For example, <b>-cropleft=50 -cropright=200</b> means to discard the
leftmost 50 and rightmost 200 columns.
<p>To specify the rectangle to keep, use <b>-left</b>, <b>-right</b>,
<b>-top</b>, <b>-bottom</b>, <b>-width</b>, <b>-height</b>, and <b>-pad</b>
options.
<p>For example, <b>-left=50 -right=200</b> means to keep the 151 columns
between Columns 50 and 200 inclusive.
<p>You can code any mixture of the options. What you don't specify defaults.
Those defaults are in favor of minimal cutting and in favor of cutting the
right and bottom edges off and (with <b>-pad</b>) minimal padding and padding
on the right and bottom. It is an error to overspecify, i.e. to specify all
three of <b>-left</b>, <b>-right</b>, and <b>-width</b> or <b>-top</b>,
<b>-bottom</b>, and <b>-height</b> or <b>right</b> as well as
<b>-cropright</b>.
<p>There is an older way to specify the rectangle to keep: positional
arguments. Arguments were the only way available before July 2000, but you
should not use them in new applications. Options are easier to remember and
read, more expressive, and allow you to use defaults.
<p>If you use both options and arguments, the two specifications get mixed in
an unspecified way.
<p>To use arguments, specify all four of the <i>left</i>, <i>top</i>,
<i>width</i>, and <i>height</i> arguments. <i>left</i> and <i>top</i> have
the same effect as specifying them as the argument of a <b>-left</b> or
<b>-top</b> option, respectively. <i>width</i> and <i>height</i> have the
same effect as specifying them as the argument of a <b>-width</b> or
<b>-height</b> option, respectively, where they are positive. Where they are
not positive, they have the same effect as specifying one less than the value
as the argument to a <b>-right</b> or <b>-bottom</b> option, respectively.
(E.g. <i>width</i> = 0 makes the cut go all the way to the right edge).
Before July 2000, negative numbers were not allowed for <i>width</i> and
<i>height</i>.
<p>Input is from Standard Input if you don't specify the input file
<i>pnmfile</i>.
<p>Output is to Standard Output.
<p><b>pamcut</b> works on a multi-image stream. It cuts each image in the
stream independently and produces a multi-image stream output. Before
Netpbm 10.32 (March 2006), it ignored all but the first image in the stream.
<p>If you are splitting a single image into multiple same-size images,
<b>pamdice</b> is faster and easier than running <b>pamcut</b>
multiple times.
<p><b>pamcomp</b> is also useful for cutting and padding an image to a
certain size. You create a background image of the desired frame
dimensions and overlay the subject image on it.
<h2 id="options">OPTIONS</h2>
<p>In addition to the options common to all programs based on libnetpbm
(most notably <b>-quiet</b>, see <a href="index.html#commonoptions">
Common Options</a>), <b>pamcut</b> recognizes the following
command line options:
<dl compact>
<dt><b>-left=</b><i>colnum</i>
<dd>The column number of the leftmost column to be in the output.
Columns left of this get cut out. If a nonnegative number, it refers
to columns numbered from 0 at the left, increasing to the right. If
negative, it refers to columns numbered -1 at the right, decreasing to
the left.
<dt><b>-right=</b><i>colnum</i>
<dd>The column number of the rightmost column to be in the output,
numbered the same as for <b>-left.</b> Columns to the right of this
get cut out.
<dt><b>-top=</b><i>rownum</i>
<dd>The row number of the topmost row to be in the output. Rows above
this get cut out. If a nonnegative number it refers to rows numbered
from 0 at the top, increasing downward. If negative, it refers to
columns numbered -1 at the bottom, decreasing upward.
<dt><b>-bottom=</b><i>rownum</i>
<dd>The row number of the bottom-most row to be in the output,
numbered the same as for <b>-top</b>. Rows below this get cut out.
<dt><b>-width=</b><i>cols</i>
<dd>The number of columns to be in the output. Must be positive.
<dt><b>-height=</b><i>rows</i>
<dd>The number of rows to be in the output. Must be positive.
<dt><b>-cropleft</b>
<dt><b>-cropright</b>
<dt><b>-croptop</b>
<dt><b>-cropbottom</b>
<dd>These options tell how many rows or columns to crop from the left,
right, top, or bottom edges, respectively.
<p>The value must not be negative.
<p>These option were new in Netpbm 10.85 (December 2018). Before that, you
can achieve the same thing with <b>-left</b>, <b>top</b>, and negative values
for <b>-right</b> and <b>-bottom</b>. Remember to subtract one in the latter
case; e.g. the equivalent of <b>-cropright=1</b> is <b>-right=-2</b>.
<dt><b>-pad</b>
<dd>If the rectangle you specify is not entirely within the input
image, <b>pamcut</b> fails unless you also specify <b>-pad</b>. In
that case, it pads the output with black up to the edges you specify.
You can use this option if you need to have an image of certain
dimensions and have an image of arbitrary dimensions.
<p><b>pnmpad</b> also adds borders to an image, but you specify their
width directly.
<p><b>pamcomp</b> does a more general form of this padding. Create a
background image of the frame dimensions and overlay the subject image
on it. You can use options to have the subject image in the center of
the frame or against any edge and make the padding any color (the padding
color is the color of the background image).
<dt><b>-reportonly</b>
<dd>
This causes <b>pamcut</b> to write to Standard Output a description of the
cutting it would have done instead of producing an output image. See
<a href="#reportonly">below</a> for a description of this output and ways
to use it.
<p>That description is one line of text, containing 8 decimal numbers of
pixels, separated by spaces:
<ol>
<li>column number of left cut
<li>column number of right cut
<li>row number of top cut
<li>row number of bottom cut
<li>width of input image
<li>height of input image
<li>width of output image
<li>height of output image
</ol>
<p>The column number of the left cut is the column number in the input image
of the leftmost column of the output image. for the right cut, it is for
the rightmost column of the output. Top and bottom are analogous.
<p><em>The column and row numbers can be negative</em> if you
specified <b>-pad</b> and <b>pamcut</b> would have added padding. Likewise,
they can be beyond the right and bottom edge of the input image.
<p>Example:
<pre>
<span style="font-family: monospace">
10 109 -1 98 150 80 100 100
</span>
</pre>
<p>This option was new in Netpbm 11.06 (March 2024).
<dt><b>-verbose</b>
<dd>
Print information about the processing to Standard Error.
</dl>
<h2 id="seealso">SEE ALSO</h2>
<b><a href="pnmcrop.html">pnmcrop</a></b>,
<b><a href="pamdice.html">pamdice</a></b>,
<b><a href="pamcomp.html">pamcomp</a></b>,
<b><a href="pnmpad.html">pnmpad</a></b>,
<b><a href="pamcat.html">pamcat</a></b>,
<b><a href="pgmslice.html">pgmslice</a></b>,
<b><a href="pnm.html">pnm</a></b>
<h2 id="history">HISTORY</h2>
<p><b>pamcut</b> was derived from <b>pnmcut</b> in Netpbm 9.20 (May 2001).
It was the first Netpbm program adapted to the new PAM format and programming
library.
<p>The predecessor <b>pnmcut</b> was one of the oldest tools in the Netpbm
package.
<h2 id="author">AUTHOR</h2>
Copyright (C) 1989 by Jef Poskanzer.
<hr>
<h2 id="index">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="#seealso">SEE ALSO</a>
<li><a href="#history">HISTORY</a>
<li><a href="#author">AUTHOR</a>
</ul>
</body>
</html>
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