Imager::Color(3pm)

1Imager::Color(3)      User Contributed Perl Documentation     Imager::Color(3)
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3
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NAME

6       Imager::Color - Color handling for Imager.
7

SYNOPSIS

9         use Imager;
10
11         $color = Imager::Color->new($red, $green, $blue);
12         $color = Imager::Color->new($red, $green, $blue, $alpha);
13         $color = Imager::Color->new("#C0C0FF"); # html color specification
14
15         $color->set($red, $green, $blue);
16         $color->set($red, $green, $blue, $alpha);
17         $color->set("#C0C0FF"); # html color specification
18
19         ($red, $green, $blue, $alpha) = $color->rgba();
20         @hsv = $color->hsv();
21
22         $color->info();
23
24         if ($color->equals(other=>$other_color)) {
25           ...
26         }
27

DESCRIPTION

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
33       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
37       •   for 3 or 4 channel images the color components are red, green,
38           blue, alpha.
39
40       •   for 1 or 2 channel images the color components are gray, alpha,
41           with the other two components ignored.
42
43       An alpha value of zero is fully transparent, an alpha value of 255 is
44       fully opaque.
45

METHODS

47       new This creates a color object to pass to functions that need a color
48           argument.
49
50       set This changes an already defined color.  Note that this does not
51           affect any places where the color has been used previously.
52
53       rgba()
54           This returns the red, green, blue and alpha channels of the color
55           the object contains.
56
57       info
58           Calling info merely dumps the relevant color to the log.
59
60       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
65           Compares all four channels unless "ignore_alpha" is set.  If
66           "ignore_alpha" is set only the first three channels are compared.
67
68       You can specify colors in several different ways, you can just supply
69       simple values:
70
71       •   an Imager::Color object
72
73       •   an Imager::Color::Float object, the ranges of samples are
74           translated from 0.0...1.0 to 0...255.
75
76       •   simple numeric parameters - if you supply 3 or 4 numeric arguments,
77           you get a color made up of those RGB (and possibly A) components.
78
79       •   a six hex digit web color, either "RRGGBB" or "#RRGGBB"
80
81       •   an eight hex digit web color, either "RRGGBBAA" or "#RRGGBBAA".
82
83       •   a CSS rgb() color, based on CSS Color 4.  The "none" keyword is not
84           supported and numbers must be simple decimals without exponents.
85           eg.
86
87             rgb(50% 50% 100%)
88             rgb(0, 0, 255)
89             rgb(0.5 0.5 1.0 / 0.8)
90             rgb(50%, 50%, 100%, 80%)
91
92           Samples from percentages or decimals are rounded up per CSS Color 3
93           and 4.
94
95           This accepts some colors not accepted by the CSS rgb()
96           specification, this may change.
97
98       •   a 3 hex digit web color, "#RGB" - a value of F becomes 255.
99
100       •   a color name, from whichever of the gimp "Named_Colors" file or X
101           "rgb.txt" is found first.  The same as using the "name" keyword.
102
103       You can supply named parameters:
104
105       •   'red', 'green' and 'blue', optionally shortened to 'r', 'g' and
106           'b'.  The color components in the range 0 to 255.
107
108            # all of the following are equivalent
109            my $c1 = Imager::Color->new(red=>100, blue=>255, green=>0);
110            my $c2 = Imager::Color->new(r=>100, b=>255, g=>0);
111            my $c3 = Imager::Color->new(r=>100, blue=>255, g=>0);
112
113       •   "hue", "saturation" and "value", optionally shortened to "h", "s"
114           and "v", to specify a HSV color.  0 <= hue < 360, 0 <= s <= 1 and 0
115           <= v <= 1.
116
117             # the same as RGB(127,255,127)
118             my $c1 = Imager::Color->new(hue=>120, v=>1, s=>0.5);
119             my $c1 = Imager::Color->new(hue=>120, value=>1, saturation=>0.5);
120
121       •   "web", which can specify a 6 or 3 hex digit web color, in any of
122           the forms "#RRGGBB", "#RGB", "RRGGBB" or "RGB".
123
124             my $c1 = Imager::Color->new(web=>'#FFC0C0'); # pale red
125
126       •   "gray" or "grey" which specifies a single channel, from 0 to 255.
127
128             # exactly the same
129             my $c1 = Imager::Color->new(gray=>128);
130             my $c1 = Imager::Color->new(grey=>128);
131
132       •   "rgb" which takes a 3 member arrayref, containing each of the red,
133           green and blue values.
134
135             # the same
136             my $c1 = Imager::Color->new(rgb=>[255, 100, 0]);
137             my $c1 = Imager::Color->new(r=>255, g=>100, b=>0);
138
139       •   "hsv" which takes a 3 member arrayref, containing each of hue,
140           saturation and value.
141
142             # the same
143             my $c1 = Imager::Color->new(hsv=>[120, 0.5, 1]);
144             my $c1 = Imager::Color->new(hue=>120, v=>1, s=>0.5);
145
146       •   "gimp" which specifies a color from a GIMP palette file.  You can
147           specify the file name of the palette file with the 'palette'
148           parameter, or let Imager::Color look in various places, typically
149           "$HOME/gimp-1.x/palettes/Named_Colors" with and without the version
150           number, and in "/usr/share/gimp/palettes/".  The palette file must
151           have color names.
152
153             my $c1 = Imager::Color->new(gimp=>'snow');
154             my $c1 = Imager::Color->new(gimp=>'snow', palette=>'testimg/test_gimp_pal);
155
156       •   "xname" which specifies a color from an X11 "rgb.txt" file.  You
157           can specify the file name of the "rgb.txt" file with the "palette"
158           parameter, or let Imager::Color look in various places, typically
159           "/usr/lib/X11/rgb.txt".
160
161             my $c1 = Imager::Color->new(xname=>'blue') # usually RGB(0, 0, 255)
162
163       •   "builtin" which specifies a color from the built-in color table in
164           Imager::Color::Table.  The colors in this module are the same as
165           the default X11 "rgb.txt" file.
166
167             my $c1 = Imager::Color->new(builtin=>'black') # always RGB(0, 0, 0)
168
169       •   "name" which specifies a name from either a GIMP palette, an X
170           "rgb.txt" file or the built-in color table, whichever is found
171           first.
172
173       •   'channel0', 'channel1', etc, each of which specifies a single
174           channel.  These can be abbreviated to 'c0', 'c1' etc.
175
176       •   'channels' which takes an arrayref of the channel values.
177
178       Optionally you can add an alpha channel to a color with the 'alpha' or
179       'a' parameter.
180
181       These color specifications can be used for both constructing new colors
182       with the new() method and modifying existing colors with the set()
183       method.
184

METHODS

186       hsv()
187               my($h, $s, $v, $alpha) = $color->hsv();
188
189           Returns the color as a Hue/Saturation/Value/Alpha tuple.
190
191       red
192       green
193       blue
194       alpha
195           Returns the respective component as an integer from 0 to 255.
196
197       as_float
198           Returns the color as a Imager::Color::Float object.
199
200       as_css_rgb
201           Returns the color as a CSS rgb() format color.  This is always
202           returned in the byte form, eg. rgb(255 128 64).
203
204           If the alpha is not full coverage (255) it will be rounded if the
205           result of converting the color back to an 8 bit color would return
206           the same alpha, eg. if the color alpha is 128, it will be formatted
207           as 0.5, not as the more precise 50.2%.
208

AUTHOR

210       Arnar M. Hrafnkelsson, addi@umich.edu And a great deal of help from
211       others - see the "README" for a complete list.
212

NAME

SYNOPSIS

DESCRIPTION

METHODS

METHODS

AUTHOR

SEE ALSO