Pamenlarge User Manual(1) General Commands Manual Pamenlarge User Manual(1)
NAME
pamenlarge - Enlarge a Netpbm image N times
SYNOPSIS
pamenlarge [-scale=integer] [-xscale=integer] [-yscale=integer] [file-
name]
pamenlarge N [pnmfile]
DESCRIPTION
This program is part of Netpbm(1).
pamenlarge reads a Netpbm image as input, replicates its pixels N
times, and produces a Netpbm image as output. The output is the same
type of image as the input.
If you enlarge by a factor of 3 or more, you should probably add a pn-
msmooth step; otherwise, you can see the original pixels in the result-
ing image.
For PBM images, pamenlarge uses special fast algorithms for scale fac-
tors up to 10. For larger factors, it uses a simple but slow algo-
rithm. As a result, you can often get a significantly faster scale by
running pamenlarge multiple times. For example, enlarging by 3 and
then by 5 is faster than enlarging once by 15. And because the algo-
rithms are different for the different scale factors, some faster than
others, the order matters too. For example, the following examples all
produce the same output -- an image 15 times bigger on edge than the
input -- but at different speeds, each being faster than the one be-
fore.
$ pamenlarge -scale=15 test.pbm
$ pamenlarge -scale=5 test.pbm | pamenlarge -scale=3
$ pamenlarge -scale=3 test.pbm | pamenlarge -scale=5
The special fast cases for factors up to 10 have existed since Release
10.50 (March 2010). The special cases for 1, 2, 3, and 5 go back to
Release 10.41 (December 2007). Before 10.41, there are no special
scale factors and PBM enlargement is significantly slower than today
for all scale factors.
pamenlarge can enlarge only by integer factors. The slower but more
general pamscale can enlarge or reduce by arbitrary factors. pamscale
allows you to enlarge by resampling, which gives you smoother enlarge-
ments. But it is much slower.
pamstretch is another enlarging program that enlarges by integer fac-
tors. It does a simple kind of resampling that gives you a smoothed
enlargement with less computational cost.
pbmreduce can reduce by integer factors, but only for PBM images.
ARGUMENTS
As with most Netpbm programs, you can give the input file name as an
argument or omit that argument and have it come from Standard Input
(and you can specify '-' for the argument to specify Standard Input ex-
plicitly).
You can also specify the scale factor as an argument, for backward com-
patibility, but the preferred way to do that is with a -scale option,
because it is easier to remember and read that way. The scale factor
argument goes before the file name argument.
OPTIONS
In addition to the options common to all programs based on libnetpbm
(most notably -quiet, see
Common Options ⟨index.html#commonoptions⟩ ), pamenlarge recognizes the
following command line options:
-scale=integer
-xscale=integer
-yscale=integer
These specify the scale factor. -xscale specifies the horizon-
tal scale factor; -yscale specifies the vertical scale factor
and -scale specifies both.
If you specify -xscale but not -yscale, pamenlarge does not
scale vertically (i.e. the vertical scale factor is 1). The
converse applies if you specify -yscale and not -xscale.
You cannot specify -scale and also -xscale or yscale.
You must specify at least one of these options, unless you use
the deprecaated method of specifying the scale factor via argu-
ment.
These options were all new in Netpbm 10.86 (March 2019). Before
that, use the scale argument.
HISTORY
pamenlarge was new in Netpbm 10.25 (October 2004). It is designed as a
replacement for pnmenlarge by Jef Poskanzer, which was in Pbmplus as
far back as 1989. The major difference is that pamenlarge can enlarge
PAM format images in addition to PNM.
SEE ALSO
pbmreduce(1), pamscale(1), pamstretch(1), pbmpscale(1), pnmsmooth(1),
pnm(1)
AUTHOR
Copyright (C) 1989 by Jef Poskanzer.
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/pamenlarge.html
netpbm documentation 07 January 2019 Pamenlarge User Manual(1)
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