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Annotated edit history of pngtopnm(1) version 1, including all changes. View license author blame.
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1 perry 1 pngtopnm
2 !!!pngtopnm
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 OPTIONS
7 SEE ALSO
8 NOTE
9 BUGS
10 AUTHORS
11 ----
12 !!NAME
13
14
15 pngtopnm - convert a Portable Network Graphics file into a portable anymap
16 !!SYNOPSIS
17
18
19 __pngtopnm__ [[-verbose] [[-alpha | -mix] [[-background
20 color]
21 [[-gamma value] [[-text file] [[-time]
22 [[''pngfile'']
23 !!DESCRIPTION
24
25
26 Reads a Portable Network Graphics as input. Produces a
27 portable anymap as output. The type of the output file
28 depends on the input file - if it's black
29 pbm'' file is written, else if it's grayscale a
30 ''pgm'' file, else a ''ppm'' file.
31 !!OPTIONS
32
33
34 __-verbose__
35
36
37 Display the format of the input file and the type of the
38 output file. If the chunks are part of the ''png-file,''
39 the alpha, transparency and gamma-values will be
40 indicated.
41
42
43 __-alpha__
44
45
46 Output the alpha channel or transparency mask of the image.
47 The result is either a ''pbm'' file or ''pgm'' file,
48 depending on whether different levels of transparency
49 appear.
50
51
52 __-mix__
53
54
55 Compose the image with the transparency or alpha mask
56 against a the background. When a background chunk is
57 available that color is taken, else black will
58 do.
59
60
61 __-background color__
62
63
64 If no background color chunck is present in the
65 ''png-file,'' or when another color is required this
66 parameter can be used to set the background color of images.
67 This is especially useful for alpha-channel images or those
68 with transparency chunks. The format, to specify the color
69 in, is either (in the case of orange)
70 ''
71
72
73 __-gamma value__
74
75
76 Converts the image to a new display-gamma value. When a gAMA
77 chunk is present in the ''png-file,'' the image-gamma
78 value will be used. When not, the image-gamma is considered
79 to be 1.0. Based on the image-gamma and the display-gamma
80 given with this option the colors written to the
81 ''pnm-file'' will be adjusted.
82 Because the gamma's of uncompensated monitors are around
83 2.6, which results in an image-gamma of 0.45, some typical
84 situations are: when the image-gamma is 0.45 (use -verbose
85 to check) and the picture is too light, your system is
86 gamma-corrected, so convert with
87
88
89 __-text file__
90
91
92 Writes the tEXt and zTXt chunks to a file, in a format as
93 described in the ''pnmtopng'' man-page. These chunks
94 contain text comments or annotations.
95
96
97 __-time__
98
99
100 Prints the tIME chunk to stderr.
101
102
103 All flags can be abbreviated to their shortest unique
104 prefix.
105 !!SEE ALSO
106
107
108 pnmtopng(1), ptot(1), pnmgamma(1), pnm(5)
109 !!NOTE
110
111
112 Instead of pngtopnm|pnmtoxxx, a specific converter should be
113 used, if available. E.g. ''ptot'' (PNG to TIFF
114 conversion), etc.
115 !!BUGS
116
117
118 There could be an option to read the comment text from pnm
119 comments instead of a separate file.
120
121
122 The program could be much faster, with a bit of code
123 optimizing.
124 !!AUTHORS
125
126
127 Copyright (C) 1995-1997 by Alexander Lehmann
128 and Willem van Schaik.
129 ----
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