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1 perry 1 pnmshear
2 !!!pnmshear
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 SEE ALSO
7 AUTHOR
8 ----
9 !!NAME
10
11
12 pnmshear - shear a portable anymap by some angle
13 !!SYNOPSIS
14
15
16 __pnmshear__ [[__-noantialias__] ''angle''
17 [[''pnmfile'']
18 !!DESCRIPTION
19
20
21 Reads a portable anymap as input. Shears it by the specified
22 angle and produces a portable anymap as output. If the input
23 file is in color, the output will be too, otherwise it will
24 be grayscale. The angle is in degrees (floating point), and
25 measures this:
26
27
28 +-------+ +-------+
29 | | |\ \
30 | OLD | | \ NEW \
31 | | |an\ \
32 +-------+ |gle+-------+
33 If the angle is negative, it shears the other way:
34
35
36 +-------+ |-an+-------+
37 | | |gl/ /
38 | OLD | |e/ NEW /
39 | | |/ /
40 +-------+ +-------+
41 The angle should not get too close to 90 or -90, or the resulting anymap will be unreasonably wide.
42
43
44 The shearing is implemented by looping over the source
45 pixels and distributing fractions to each of the destination
46 pixels. This has an
47 -noantialias__ flag. This does
48 the shearing by moving pixels without changing their values.
49 If you want anti-aliasing and don't care about the precise
50 colors, but still need a limited *number* of colors, you can
51 run the result through ''ppmquant''.
52
53
54 All flags can be abbreviated to their shortest unique
55 prefix.
56 !!SEE ALSO
57
58
59 pnmrotate(1), pnmflip(1), pnm(5), ppmquant(1)
60 !!AUTHOR
61
62
63 Copyright (C) 1989, 1991 by Jef Poskanzer.
64 ----
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