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
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13       [-xscale=X]
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15       [-yscale=Y] [-blackedge]
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17       [-dropedge]
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19       N
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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-
39       gen(1)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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PARAMETERS

52       The  N  parameter  is  the scale factor.  It is valid only if you don't
53       specify -xscale or -yscale.  In that case, pamstretch  scales  in  both
54       dimensions and by the scale factor N.
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OPTIONS

58       -xscale=X
59              This is the horizontal scale factor.  If you don't specify this,
60              but do specify a vertical scale  factor,  the  horizontal  scale
61              factor is 1.
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64       -yscale=Y
65              This  is  the vertical scale factor.  If you don't specify this,
66              but do specify a horizontal scale  factor,  the  vertical  scale
67              factor is 1.
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70       -blackedge
71              interpolate to black at right/bottom edges.
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74       -dropedge
75              drop  one (source) pixel at right/bottom edges. This is arguably
76              more logical than the default behaviour, but it means  producing
77              output which is a slightly odd size.
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BUGS

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

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

93       Russell Marks (russell.marks@ntlworld.com).
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97netpbm documentation           11 November 2001      Pamstretch User Manual(0)