1Pamenlarge User Manual(0) Pamenlarge User Manual(0)
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6 pamenlarge - Enlarge a Netpbm image N times by duplicating pixels
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10 pamenlarge [-scale=integer] [-xscale=integer] [-yscale=integer] [file‐
11 name]
12 pamenlarge N [pnmfile]
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18 This program is part of Netpbm(1).
19 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.
23 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.
27 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.
38 $ pamenlarge -scale=15 test.pbm
40 $ pamenlarge -scale=5 test.pbm | pamenlarge -scale=3
41 $ pamenlarge -scale=3 test.pbm | pamenlarge -scale=5
42 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.
49 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.
54 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.
58 pbmreduce can reduce by integer factors, but only for PBM images.
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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).
67 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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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:
82 -scale=integer
86 -xscale=integer
88 -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.
93 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.
97 You cannot specify -scale and also -xscale or yscale.
99 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.
103 These options were all new in Netpbm 10.86 (March 2019). Before
105 that, use the scale argument.
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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.
116
120 pbmreduce(1), pamscale(1), pamstretch(1), pbmpscale(1), pnmsmooth(1),
121 pnm(1)
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125 Copyright (C) 1989 by Jef Poskanzer.
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128 This manual page was generated by the Netpbm tool 'makeman' from HTML
129 source. The master documentation is at
130 http://netpbm.sourceforge.net/doc/pamenlarge.html
132netpbm documentation 07 January 2019 Pamenlarge User Manual(0)