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1 perry 1 ppmchange
2 !!!ppmchange
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 OPTIONS
7 SEE ALSO
8 AUTHOR
9 ----
10 !!NAME
11
12
13 ppmchange - change all pixels of one color to another in a portable pixmap
14 !!SYNOPSIS
15
16
17 __ppmchange__ [[ __-closeness__
18 ''closeness_percent'' ] [[ __-remainder__
19 ''remainder_color'' ] [[ ''oldcolor newcolor'' ] ...
20 [[''ppmfile'']
21 !!DESCRIPTION
22
23
24 Reads a portable pixmap as input. Changes all pixels of
25 ''oldcolor'' to ''newcolor''. You may specify up to
26 256 oldcolor/newcolor pairs on the command line.
27 __ppmchange__ leaves all colors not mentioned unchanged,
28 unless you specify the __-remainder__ option, in which
29 case they are all changed to the single specified
30 color.
31
32
33 You can specify that colors similar, but not identical, to
34 the ones you specify get replaced by specifying a
35
36
37 The colors can be specified in five ways:
38
39
40 o
41
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43 A name, assuming that a pointer to an X11-style color names
44 file was compiled in.
45
46
47 o
48
49
50 An X11-style hexadecimal specifier: rgb:r/g/b, where r g and
51 b are each 1- to 4-digit hexadecimal numbers.
52
53
54 o
55
56
57 An X11-style decimal specifier: rgbi:r/g/b, where r g and b
58 are floating point numbers between 0 and 1.
59
60
61 o
62
63
64 For backwards compatibility, an old-X11-style hexadecimal
65 number: #rgb, #rrggbb, #rrrgggbbb, or
66 #rrrrggggbbbb.
67
68
69 o
70
71
72 For backwards compatibility, a triplet of numbers separated
73 by commas: r,g,b, where r g and b are floating point numbers
74 between 0 and 1. (This style was added before MIT came up
75 with the similar rgbi style.)
76
77
78 If a pixel matches two different ''oldcolor''s,
79 __ppmchange__ replaces it with the ''newcolor'' of the
80 leftmost specified one.
81 !!OPTIONS
82
83
84 __-closeness__ ''closeness_percent''
85
86
87 ''closeness'' is an integer per centage indicating how
88 close to the color you specified a pixel must be to get
89 replaced. By default, it is 0, which means the pixel must be
90 the exact color you specified.
91
92
93 A pixel gets replaced if the distance in color between it
94 and the color you specified is less than or equal to
95 ''closeness''.
96
97
98 The
99
100
101 This is probably simpler than what you want most the time.
102 You probably would like to change colors that have similar
103 chrominance, regardless of their intensity. So if there's a
104 red barn that is variously shadowed, you want the entire
105 barn changed. But because the shadowing significantly
106 changes the color according to __ppmchange__'s distance
107 formula, parts of the barn are probably about as distant in
108 color from other parts of the barn as they are from green
109 grass next to the barn.
110
111
112 Maybe __ppmchange__ will be enhanced some day to do
113 chrominance analysis.
114
115
116 __-remainder__ ''color''
117
118
119 __ppmchange__ changes all pixels which are not of a color
120 for which you specify an explicit replacement color on the
121 command line to color ''color''.
122
123
124 An example application of this is
125
126
127 __ppmchange -remainder=black red red__
128
129
130 to lift only the red portions from an image, or
131
132
133 __ppmchange -remainder=black red white |
134 ppmtopgm__
135
136
137 to create a mask file for the red portions of the
138 image.
139 !!SEE ALSO
140
141
142 pgmtoppm(1), ppmcolormask(1),
143 ppm(5)
144 !!AUTHOR
145
146
147 Wilson H. Bent. Jr. (whb@usc.edu) with modifications by
148 Alberto Accomazzi (alberto@cfa.harvard.edu)
149 ----
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