Manual: pamenlarge

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] [filename]

       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 pnmsmooth step; otherwise, you can see the  origi‐
       nal pixels in the resulting image.

       For  PBM	 images,  pamenlarge uses special fast algorithms for scale factors 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  multi‐
       ple  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 dif‐
       ferent 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 Release 10.41 (December 2007).	Before 10.41, there are no special scale factors and PBM en‐
       largement 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  arbi‐
       trary  factors.	pamscale allows you to enlarge by resampling, which gives you smoother enlargements.  But it is much
       slower.

       pamstretch is another enlarging program that enlarges by integer factors.  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 explicitly).

       You can also specify the scale factor as an argument, for backward compatibility, 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 ), pa‐
       menlarge 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 argument.

	      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)