1Pamstretch User Manual(0)                            Pamstretch User Manual(0)
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NAME

6       pamstretch  - scale up a PNM or PAM image by interpolating between pix‐
7       els.
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SYNOPSIS

11       pamstretch
12
13       [-xscale=X]
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15       [-yscale=Y] [-blackedge]
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17       [-dropedge]
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19       N
20
21       [infile]
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23       You can use the minimum unique abbreviation of the  options.   You  can
24       use  two  hyphens instead of one.  You can separate an option name from
25       its value with white space instead of an equals sign.
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DESCRIPTION

29       This program is part of Netpbm(1).
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31       pamstretch  scales up pictures by integer  values,  either  vertically,
32       horizontally,  or  both.   pamstretch  differs from pamscale and pamen‐
33       large in that when it inserts the additional rows and columns,  instead
34       of  making  the  new  row  or column a copy of its neighbor, pamstretch
35       makes the new row or column an interpolation between its neighbors.  In
36       some images, this produces better looking output.
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38       To scale up to non-integer pixel sizes, e.g. 2.5, try pamstretch-gen(1)
39       instead.
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41       Options  let  you  select  alternative  methods  of  dealing  with  the
42       right/bottom  edges  of  the  picture.  Since the interpolation is done
43       between the top-left corners of the scaled-up pixels, it's not  obvious
44       what  to  do  with the right/bottom edges.  The default behaviour is to
45       scale those up without interpolation (more precisely, the right edge is
46       only  interpolated vertically, and the bottom edge is only interpolated
47       horizontally), but there are two other possibilities, selected  by  the
48       -blackedge and -dropedge options.
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50       In  the  special  case  that the stretch factor is 1, there is no issue
51       with the right and bottom edges, the edges of the output are  identical
52       to the edges of the input regardless of -blackedge and -dropedge.  How‐
53       ever, before Netpbm 10.86 (March 2019), -dropedge would cause the  edge
54       to be dropped even where the stretch factor was 1.
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PARAMETERS

59       The  N  parameter  is  the scale factor.  It is valid only if you don't
60       specify -xscale or -yscale.  In that case, pamstretch  scales  in  both
61       dimensions and by the scale factor N.
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63       Before Netpbm 10.86 (March 2019), 1 was not a valid value.
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OPTIONS

68       In  addition  to  the options common to all programs based on libnetpbm
69       (most notably -quiet, see
70        Common Options ⟨index.html#commonoptions⟩ ), pamstretch recognizes the
71       following command line options:
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75       -xscale=X
76              This is the horizontal scale factor.  If you don't specify this,
77              but do specify a vertical scale  factor,  the  horizontal  scale
78              factor is 1.
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80              This option was new in Netpbm 9.21 (December 2001).
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83       -yscale=Y
84              This  is  the vertical scale factor.  If you don't specify this,
85              but do specify a horizontal scale  factor,  the  vertical  scale
86              factor is 1.
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88              This option was new in Netpbm 9.21 (December 2001).
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91       -blackedge
92              interpolate to black at right/bottom edges.
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95       -dropedge
96              drop  one (source) pixel at right/bottom edges. This is arguably
97              more logical than the default behaviour, but it means  producing
98              output which is a slightly odd size.
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LIMITATIONS

104       Usually produces fairly ugly output for PBMs. For most PBM input you'll
105       probably want to reduce the `noise' first using something  like  pnmnl‐
106       filt(1).
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SEE ALSO

110       pamstretch-gen(1), pamenlarge(1), pamscale(1), pnmnlfilt(1)
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AUTHOR

114       Russell Marks (russell.marks@ntlworld.com).
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DOCUMENT SOURCE

117       This  manual  page was generated by the Netpbm tool 'makeman' from HTML
118       source.  The master documentation is at
119
120              http://netpbm.sourceforge.net/doc/pamstretch.html
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122netpbm documentation           02 February 2019      Pamstretch User Manual(0)
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