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 original 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 multiple times.  For example, enlarging by 3 and then by 5 is  faster  than  enlarging
       once  by  15.  And because the algorithms 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
       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 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
       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 ), 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 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)