1Imager::Color(3) User Contributed Perl Documentation Imager::Color(3)
2
6 Imager::Color - Color handling for Imager.
7
9 use Imager;
10 $color = Imager::Color->new($red, $green, $blue);
12 $color = Imager::Color->new($red, $green, $blue, $alpha);
13 $color = Imager::Color->new("#C0C0FF"); # html color specification
14 $color->set($red, $green, $blue);
16 $color->set($red, $green, $blue, $alpha);
17 $color->set("#C0C0FF"); # html color specification
18 ($red, $green, $blue, $alpha) = $color->rgba();
20 @hsv = $color->hsv();
21 $color->info();
23 if ($color->equals(other=>$other_color)) {
25 ...
26 }
27
29 This module handles creating color objects used by Imager. The idea is
30 that in the future this module will be able to handle color space
31 calculations as well.
32 An Imager color consists of up to four components, each in the range 0
34 to 255. Unfortunately the meaning of the components can change
35 depending on the type of image you're dealing with:
36 · for 3 or 4 channel images the color components are red, green,
38 blue, alpha.
39 · for 1 or 2 channel images the color components are gray, alpha,
41 with the other two components ignored.
42 An alpha value of zero is fully transparent, an alpha value of 255 is
44 fully opaque.
45
47 new This creates a color object to pass to functions that need a color
48 argument.
49 set This changes an already defined color. Note that this does not
51 affect any places where the color has been used previously.
52 rgba()
54 This returns the red, green, blue and alpha channels of the color
55 the object contains.
56 info
58 Calling info merely dumps the relevant color to the log.
59 equals(other=>$other_color)
61 equals(other=>$other_color, ignore_alpha=>1)
62 Compares $self and color $other_color returning true if the color
63 components are the same.
64 Compares all four channels unless "ignore_alpha" is set. If
66 "ignore_alpha" is set only the first three channels are compared.
67 You can specify colors in several different ways, you can just supply
69 simple values:
70 · simple numeric parameters - if you supply 3 or 4 numeric arguments,
72 you get a color made up of those RGB (and possibly A) components.
73 · a six hex digit web color, either "RRGGBB" or "#RRGGBB"
75 · an eight hex digit web color, either "RRGGBBAA" or "#RRGGBBAA".
77 · a 3 hex digit web color, "#RGB" - a value of F becomes 255.
79 · a color name, from whichever of the gimp "Named_Colors" file or X
81 "rgb.txt" is found first. The same as using the "name" keyword.
82 You can supply named parameters:
84 · 'red', 'green' and 'blue', optionally shortened to 'r', 'g' and
86 'b'. The color components in the range 0 to 255.
87 # all of the following are equivalent
89 my $c1 = Imager::Color->new(red=>100, blue=>255, green=>0);
90 my $c2 = Imager::Color->new(r=>100, b=>255, g=>0);
91 my $c3 = Imager::Color->new(r=>100, blue=>255, g=>0);
92 · "hue", "saturation" and "value", optionally shortened to "h", "s"
94 and "v", to specify a HSV color. 0 <= hue < 360, 0 <= s <= 1 and 0
95 <= v <= 1.
96 # the same as RGB(127,255,127)
98 my $c1 = Imager::Color->new(hue=>120, v=>1, s=>0.5);
99 my $c1 = Imager::Color->new(hue=>120, value=>1, saturation=>0.5);
100 · "web", which can specify a 6 or 3 hex digit web color, in any of
102 the forms "#RRGGBB", "#RGB", "RRGGBB" or "RGB".
103 my $c1 = Imager::Color->new(web=>'#FFC0C0'); # pale red
105 · "gray" or "grey" which specifies a single channel, from 0 to 255.
107 # exactly the same
109 my $c1 = Imager::Color->new(gray=>128);
110 my $c1 = Imager::Color->new(grey=>128);
111 · "rgb" which takes a 3 member arrayref, containing each of the red,
113 green and blue values.
114 # the same
116 my $c1 = Imager::Color->new(rgb=>[255, 100, 0]);
117 my $c1 = Imager::Color->new(r=>255, g=>100, b=>0);
118 · "hsv" which takes a 3 member arrayref, containing each of hue,
120 saturation and value.
121 # the same
123 my $c1 = Imager::Color->new(hsv=>[120, 0.5, 1]);
124 my $c1 = Imager::Color->new(hue=>120, v=>1, s=>0.5);
125 · "gimp" which specifies a color from a GIMP palette file. You can
127 specify the file name of the palette file with the 'palette'
128 parameter, or let Imager::Color look in various places, typically
129 "$HOME/gimp-1.x/palettes/Named_Colors" with and without the version
130 number, and in "/usr/share/gimp/palettes/". The palette file must
131 have color names.
132 my $c1 = Imager::Color->new(gimp=>'snow');
134 my $c1 = Imager::Color->new(gimp=>'snow', palette=>'testimg/test_gimp_pal);
135 · "xname" which specifies a color from an X11 "rgb.txt" file. You
137 can specify the file name of the "rgb.txt" file with the "palette"
138 parameter, or let Imager::Color look in various places, typically
139 "/usr/lib/X11/rgb.txt".
140 my $c1 = Imager::Color->new(xname=>'blue') # usually RGB(0, 0, 255)
142 · "builtin" which specifies a color from the built-in color table in
144 Imager::Color::Table. The colors in this module are the same as
145 the default X11 "rgb.txt" file.
146 my $c1 = Imager::Color->new(builtin=>'black') # always RGB(0, 0, 0)
148 · "name" which specifies a name from either a GIMP palette, an X
150 "rgb.txt" file or the built-in color table, whichever is found
151 first.
152 · 'channel0', 'channel1', etc, each of which specifies a single
154 channel. These can be abbreviated to 'c0', 'c1' etc.
155 · 'channels' which takes an arrayref of the channel values.
157 Optionally you can add an alpha channel to a color with the 'alpha' or
159 'a' parameter.
160 These color specifications can be used for both constructing new colors
162 with the new() method and modifying existing colors with the set()
163 method.
164
166 hsv()
167 my($h, $s, $v, $alpha) = $color->hsv();
168 Returns the color as a Hue/Saturation/Value/Alpha tuple.
170
172 Arnar M. Hrafnkelsson, addi@umich.edu And a great deal of help from
173 others - see the "README" for a complete list.
174
176 Imager(3), Imager::Color http://imager.perl.org/
177perl v5.30.1 2020-01-30 Imager::Color(3)