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

6       pamenlarge - Enlarge a Netpbm image N times
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SYNOPSIS

10       pamenlarge N [pnmfile]
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DESCRIPTION

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

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

66       pbmreduce(1), pamscale(1), pamstretch(1),  pbmpscale(1),  pnmsmooth(1),
67       pnm(1)
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AUTHOR

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

74       This  manual  page was generated by the Netpbm tool 'makeman' from HTML
75       source.  The master documentation is at
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77              http://netpbm.sourceforge.net/doc/pamenlarge.html
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79netpbm documentation             17 March 2010       Pamenlarge User Manual(0)
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