Pamenlarge User Manual(1) General Commands Manual Pamenlarge User Manual(1)
NAME
pamenlarge - Enlarge a Netpbm image N times by duplicating pixels
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 algorithm.
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 algorithms are dif-
ferent for the different scale factors, some faster than others, the or-
der 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 before.
$ 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 Re-
lease 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 en-
largement 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 ar-
gument or omit that argument and have it come from Standard Input (and
you can specify '-' for the argument to specify Standard Input explic-
itly).
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 ]8;;index.html#commonoptions\ Common Options]8;;\ ), pamenlarge recognizes the
following command line options:
-scale=integer
-xscale=integer
-yscale=integer
These specify the scale factor. -xscale specifies the horizontal
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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