1Pamenlarge User Manual(0)                            Pamenlarge User Manual(0)
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NAME

6       pamenlarge - Enlarge a Netpbm image N times by duplicating pixels
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SYNOPSIS

10       pamenlarge  [-scale=integer] [-xscale=integer] [-yscale=integer] [file‐
11       name]
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13       pamenlarge N [pnmfile]
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DESCRIPTION

18       This program is part of Netpbm(1).
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20       pamenlarge reads a Netpbm image  as  input,  replicates  its  pixels  N
21       times,  and  produces a Netpbm image as output.  The output is the same
22       type of image as the input.
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24       If you enlarge by a factor of 3 or more, you should probably add a  pn‐
25       msmooth step; otherwise, you can see the original pixels in the result‐
26       ing image.
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28       For PBM images, pamenlarge uses special fast algorithms for scale  fac‐
29       tors  up  to  10.   For larger factors, it uses a simple but slow algo‐
30       rithm.  As a result, you can often get a significantly faster scale  by
31       running  pamenlarge  multiple  times.   For example, enlarging by 3 and
32       then by 5 is faster than enlarging once by 15.  And because  the  algo‐
33       rithms  are different for the different scale factors, some faster than
34       others, the order matters too.  For example, the following examples all
35       produce  the  same  output -- an image 15 times bigger on edge than the
36       input -- but at different speeds, each being faster than  the  one  be‐
37       fore.
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39            $ pamenlarge -scale=15 test.pbm
40            $ pamenlarge -scale=5 test.pbm | pamenlarge -scale=3
41            $ pamenlarge -scale=3 test.pbm | pamenlarge -scale=5
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44       The  special fast cases for factors up to 10 have existed since Release
45       10.50 (March 2010).  The special cases for 1, 2, 3, and 5  go  back  to
46       Release  10.41  (December  2007).   Before  10.41, there are no special
47       scale factors and PBM enlargement is significantly  slower  than  today
48       for all scale factors.
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50       pamenlarge  can  enlarge  only by integer factors.  The slower but more
51       general pamscale can enlarge or reduce by arbitrary factors.   pamscale
52       allows  you to enlarge by resampling, which gives you smoother enlarge‐
53       ments.  But it is much slower.
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55       pamstretch is another enlarging program that enlarges by  integer  fac‐
56       tors.   It  does  a simple kind of resampling that gives you a smoothed
57       enlargement with less computational cost.
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59       pbmreduce can reduce by integer factors, but only for PBM images.
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ARGUMENTS

63       As with most Netpbm programs, you can give the input file  name  as  an
64       argument  or  omit  that  argument and have it come from Standard Input
65       (and you can specify '-' for the argument to specify Standard Input ex‐
66       plicitly).
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68       You can also specify the scale factor as an argument, for backward com‐
69       patibility, but the preferred way to do that is with a  -scale  option,
70       because  it  is easier to remember and read that way.  The scale factor
71       argument goes before the file name argument.
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OPTIONS

78       In addition to the options common to all programs  based  on  libnetpbm
79       (most notably -quiet, see
80        Common Options ⟨index.html#commonoptions⟩ ), pamenlarge recognizes the
81       following command line options:
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85       -scale=integer
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87       -xscale=integer
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89       -yscale=integer
90              These specify the scale factor.  -xscale specifies the  horizon‐
91              tal  scale  factor;  -yscale specifies the vertical scale factor
92              and -scale specifies both.
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94              If you specify -xscale but  not  -yscale,  pamenlarge  does  not
95              scale  vertically  (i.e.  the  vertical scale factor is 1).  The
96              converse applies if you specify -yscale and not -xscale.
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98              You cannot specify -scale and also -xscale or yscale.
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100              You must specify at least one of these options, unless  you  use
101              the  deprecaated method of specifying the scale factor via argu‐
102              ment.
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104              These options were all new in Netpbm 10.86 (March 2019).  Before
105              that, use the scale argument.
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HISTORY

112       pamenlarge was new in Netpbm 10.25 (October 2004).  It is designed as a
113       replacement for pnmenlarge by Jef Poskanzer, which was  in  Pbmplus  as
114       far  back as 1989.  The major difference is that pamenlarge can enlarge
115       PAM format images in addition to PNM.
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SEE ALSO

120       pbmreduce(1), pamscale(1), pamstretch(1),  pbmpscale(1),  pnmsmooth(1),
121       pnm(1)
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AUTHOR

125       Copyright (C) 1989 by Jef Poskanzer.
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DOCUMENT SOURCE

128       This  manual  page was generated by the Netpbm tool 'makeman' from HTML
129       source.  The master documentation is at
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131              http://netpbm.sourceforge.net/doc/pamenlarge.html
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133netpbm documentation            07 January 2019      Pamenlarge User Manual(0)
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