Pnmpad User Manual(1) General Commands Manual Pnmpad User Manual(1)
NAME
pnmpad - add borders to a PNM image
SYNOPSIS
pnmpad [-white|-black] [-width=pixels] [-halign=ratio] [-mwidth=pixels]
[-left=pixels] [-right=pixels] [-height=pixels] [-valign=ratio]
[-mheight=pixels] [-top=pixels] [-bottom=pixels] [-reportonly] [-ver-
bose] [pnmfile]
DESCRIPTION
This program is part of Netpbm(1).
pnmpad reads a PNM image as input and outputs a PNM image that is the
input image plus black or white borders of the sizes specified.
If you just need to convert an image to a certain size regardless of
the original dimensions, pamcut with the -pad option may be a better
choice.
pnmmargin does essentially the same thing, but allows you to add bor-
ders of any color and requires all four borders to be the same size.
You can use pamcomp to add borders of any content - solid color,
pattern, or whatever. For example, if you wanted to add 10 pixels of
red
borders to the top and bottom of a 100x100 image, you could create a
100x120 red image (e.g. with ppmmake) and then use pamcomp
to insert your 100x100 image into the center of it.
OPTIONS
In addition to the options common to all programs based on libnetpbm
(most notably -quiet, see
Common Options ⟨index.html#commonoptions⟩ ), pnmpad recognizes the
following command line options:
All options can be abbreviated to their shortest unique prefix. You
may use two hyphens instead of one to designate an option. You may use
either white space or an equals sign between an option name and its
value.
-white
-black Set pad color. Default is -black.
-left=pixels
-right=pixels
-width=width
-halign=ratio
-mwidth=pixels
Specify amount of left and right padding in pixels.
-left and -right directly specify the amount of padding added to
the left and right sides, respectively, of the image.
Alternatively, you can specify -width and just one of -left and
-right and pnmpad calculates the required padding on the other
side to make the output width pixels wide. If the -width value
is less than the width of the input image plus the specified
padding, pnmpad ignores -width.
If you specify all three of -width, -left, and -right, you must
ensure that the -left and -right padding are sufficient to make
the image at least as wide as -width specifies. Otherwise, pnm-
pad fails.
When you specify -width without -left or -right, and -width is
larger than the input image, pnmpad chooses left and right pad-
ding amounts in a certain ratio. That ratio defaults to half,
but you can set it to anything (from 0 to 1) with the -halign
option. If the input image is already at least as wide as
-width specifies, pnmpad adds no padding.
Common values for -halign are:
0.0 left aligned
0.5 center aligned (default)
1.0 right aligned
-mwidth=pixels says to pad to a multiple of pixels pixels. E.g.
if pixels is 10, the output image width will be a multiple of 10
pixels. pnmpad adds to whatever padding the other options say
to do to get to this multiple. It divides that padding between
the left and right sides of the image to maintain the ratio the
other options produce. E.g. if you say -left=10 -right=10
-mwidth=50 with a 100-pixel image, you end up with a 150-pixel
image with the extra padding split evenly between left and right
for a total of 25 pixels of padding on the left and 25 on the
right. If the other options indicate no padding, pnmpad adds
padding in the ratio specified by -halign and if -halign is not
specified, equally on both sides.
Before Netpbm 10.97 (December 2021), pnmpad does not allow
-halign with -mwidth and adds padding only on the right when
-mwidth is specified and the other options indicate no padding.
Before Netpbm 10.72 (September 2015), there is no -mwidth.
Before Netpbm 10.23 (July 2004), pnmpad did not allow the -left
or -right option together with -width.
-top=pixels
-bottom=pixels
-height=height
-valign=ratio
-mheight=pixels
These options determine the vertical padding. They are analo-
gous to the horizontal padding options above.
-reportonly
This causes pnmpad to write to Standard Output a description
of the
padding it would have done instead of producing an output im-
age. See
below ⟨#reportonly⟩ for a description of this output and ways
to use it.
This option was new in Netpbm 10.89 (December 2019).
-verbose
This causes verbose messages.
REPORT ONLY
When you specify -reportonly, pnmpad does not produce an
output image. Instead, it writes to Standard Output a description of
the
padding it would have done without -reportonly.
That description is one line of text, containing 6 decimal numbers of
pixels, separated by spaces:
• left padding
• right padding
• top padding
• bottom padding
• output width
• output height
Example:
4 3 0 2 100 100
One use for this is to make padding which is fancier than the black and
white that pnmpad can do.
In the following example, we pad an image with 10 pixels of gray all
around, without knowing the original image dimensions beforehand. We
do
this by generating a gray image with pbmmake and then pasting the
subject image into the middle of it.
The example uses shell arrays, such as exist in Bash, but not Dash.
pad=($(pnmpad -reportonly -left=10 -right=10 -top=10 -bottom=10 input.ppm))
pbmmake -gray ${pad[4]} ${pad[5]} | \
pnmpaste input.ppm ${pad[0]} ${pad[2]} -
HISTORY
Before February 2002, pnmpad had a different option syntax which was
less expressive and not like conventional Netpbm programs. That syntax
is still understood by pnmpad for backward compatibility, but not docu-
mented or supported for future use.
SEE ALSO
pbmmake(1), pnmpaste(1), pamcut(1), pnmcrop(1), pamcomp(1), pnmmar-
gin(1), pbm(1)
AUTHOR
Copyright (C) 2002 by Martin van Beilen
Copyright (C) 1990 by Angus Duggan
Copyright (C) 1989 by Jef Poskanzer.
Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted, pro-
vided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in sup-
porting documentation. This software is provided "as is" without ex-
press or implied warranty.
DOCUMENT SOURCE
This manual page was generated by the Netpbm tool 'makeman' from HTML
source. The master documentation is at
http://netpbm.sourceforge.net/doc/pnmpad.html
netpbm documentation 25 December 2021 Pnmpad User Manual(1)
Generated by dwww version 1.15 on Sat Jun 29 02:02:42 CEST 2024.