1GIFTOOL(1)                   GIFLIB Documentation                   GIFTOOL(1)
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NAME

6       giftool - GIF transformation tool
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SYNOPSIS

9       giftool [-a aspect] [-b bgcolor] [-d delaytime] [-i interlacing]
10               [-n imagelist] [-p left,top] [-s width,height] [-t transcolor]
11               [-u sort-flag] [-x disposal] [-z sort-flag]
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DESCRIPTION

14       A filter for transforming GIFS. With no options, it's an expensive copy
15       of a GIF in standard input to standard output. Options specify
16       filtering operations and are performed in the order specified on the
17       command line.
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19       The -n option selects images, allowing the tool to act on a subset of
20       images in a multi-image GIF. This option takes a comma-separated list
21       of decimal integers which are interpreted as 1-origin image indices;
22       these are the images that will be acted on. If no -n option is
23       specified, the tool will select and transform all images.
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25       The -b option takes a decimal integer argument and uses it to set the
26       (0-origin) screen background color index.
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28       The -f option accepts a printf-style format string and substitutes into
29       it the values of image-descriptor and graphics-control fields. The
30       string is formatted and output once for each selected image. Normal
31       C-style escapes \b, \f, \n, \r, \t. \v, and \xNN are interpreted; also
32       \e produces ESC (ASCII 0x1b). The following format cookies are
33       substituted:
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35       %a
36           Pixel aspect byte.
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38       %b
39           Screen background color.
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41       %d
42           Image delay time
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44       %h
45           Image height (y dimension)
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47       %n
48           Image index
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50       %p
51           Image position (as an x,y pair)
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53       %s
54           Screen size (as an x,y pair)
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56       %t
57           Image transparent-color index
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59       %u
60           Image user-input flag (boolean)
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62       %v
63           GIF version string
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65       %w
66           Image width (x dimension)
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68       %x
69           Image GIF89 disposal mode
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71       %z
72           Image's color table sort flag (boolean, false if no local color
73           map)
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75       Boolean substitutions may take a prefix to modify how they are
76       displayed:
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78       1
79           "1" or "0"
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81       o
82           "on" or "off"
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84       t
85           "t" or "f"
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87       y
88           "yes" or "no"
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90       Thus, for example, "%oz" displays image sort flags using the strings
91       "on" and "off". The default with no prefix is numeric.
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93       The -a option takes an unsigned decimal integer argument and uses it to
94       set the aspect-ratio bye in the logical screen descriptor block.
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96       The -b option takes an unsigned decimal integer argument and uses it to
97       set the background color index in the logical screen descriptor block.
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99       The -d option takes a decimal integer argument and uses it to set a
100       delay time, in hundredths of a second, on selected images.
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102       The -i option sets or clears interlaccing in selected images.
103       Acceptable arguments are "1", "0", "yes", "no", "on", "off", "t", "f"
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105       The -p option takes a (0-origin) x,y coordinate-pair and sets it as the
106       preferred upper-left-corner coordinates of selected images.
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108       The -s option takes a (0-origin) x,y coordinate-pair and sets it as the
109       expected display screen size.
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111       The -t option takes a decimal integer argument and uses it to set the
112       (0-origin) index of the transparency color in selected images.
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114       The -u option sets or clears the user-input flag in selected images.
115       Acceptable arguments are "1", "0", "yes", "no", "on", "off", "t", "f".
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117       The -x option takes a decimal integer argument and uses it to set the
118       GIF89 disposal mode in selected images.
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120       The -z option sets or clears the color-table sort flag in selected
121       images. Acceptable arguments are "1", "0", "yes", "no", "on", "off",
122       "t", "f".
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124       Note that the -a, -b, -p, -s, and -z options are included to complete
125       the ability to modify all fields defined in the GIF standard, but
126       should have no effect on how an image renders on browsers or modern
127       viewers.
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AUTHOR

130       Eric S. Raymond.
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134GIFLIB                            3 June 2012                       GIFTOOL(1)
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