oracular (3) Imager::Color.3pm.gz
NAME
Imager::Color - Color handling for Imager.
SYNOPSIS
use Imager;
$color = Imager::Color->new($red, $green, $blue);
$color = Imager::Color->new($red, $green, $blue, $alpha);
$color = Imager::Color->new("#C0C0FF"); # html color specification
$color->set($red, $green, $blue);
$color->set($red, $green, $blue, $alpha);
$color->set("#C0C0FF"); # html color specification
($red, $green, $blue, $alpha) = $color->rgba();
@hsv = $color->hsv();
$color->info();
if ($color->equals(other=>$other_color)) {
...
}
DESCRIPTION
This module handles creating color objects used by Imager. The idea is that in the future this module
will be able to handle color space calculations as well.
An Imager color consists of up to four components, each in the range 0 to 255. Unfortunately the meaning
of the components can change depending on the type of image you're dealing with:
• for 3 or 4 channel images the color components are red, green, blue, alpha.
• for 1 or 2 channel images the color components are gray, alpha, with the other two components
ignored.
An alpha value of zero is fully transparent, an alpha value of 255 is fully opaque.
METHODS
new This creates a color object to pass to functions that need a color argument.
set This changes an already defined color. Note that this does not affect any places where the color has
been used previously.
rgba()
This returns the red, green, blue and alpha channels of the color the object contains.
info
Calling info merely dumps the relevant color to the log.
equals(other=>$other_color)
equals(other=>$other_color, ignore_alpha=>1)
Compares $self and color $other_color returning true if the color components are the same.
Compares all four channels unless "ignore_alpha" is set. If "ignore_alpha" is set only the first
three channels are compared.
You can specify colors in several different ways, you can just supply simple values:
• an Imager::Color object
• an Imager::Color::Float object, the ranges of samples are translated from 0.0...1.0 to 0...255.
• simple numeric parameters - if you supply 3 or 4 numeric arguments, you get a color made up of those
RGB (and possibly A) components.
• a six hex digit web color, either "RRGGBB" or "#RRGGBB"
• an eight hex digit web color, either "RRGGBBAA" or "#RRGGBBAA".
• a CSS rgb() color, based on CSS Color 4. The "none" keyword is not supported and numbers must be
simple decimals without exponents. eg.
rgb(50% 50% 100%)
rgb(0, 0, 255)
rgb(0.5 0.5 1.0 / 0.8)
rgb(50%, 50%, 100%, 80%)
Samples from percentages or decimals are rounded up per CSS Color 3 and 4.
This accepts some colors not accepted by the CSS rgb() specification, this may change.
• a 3 hex digit web color, "#RGB" - a value of F becomes 255.
• a color name, from whichever of the gimp "Named_Colors" file or X "rgb.txt" is found first. The same
as using the "name" keyword.
You can supply named parameters:
• 'red', 'green' and 'blue', optionally shortened to 'r', 'g' and 'b'. The color components in the
range 0 to 255.
# all of the following are equivalent
my $c1 = Imager::Color->new(red=>100, blue=>255, green=>0);
my $c2 = Imager::Color->new(r=>100, b=>255, g=>0);
my $c3 = Imager::Color->new(r=>100, blue=>255, g=>0);
• "hue", "saturation" and "value", optionally shortened to "h", "s" and "v", to specify a HSV color. 0
<= hue < 360, 0 <= s <= 1 and 0 <= v <= 1.
# the same as RGB(127,255,127)
my $c1 = Imager::Color->new(hue=>120, v=>1, s=>0.5);
my $c1 = Imager::Color->new(hue=>120, value=>1, saturation=>0.5);
• "web", which can specify a 6 or 3 hex digit web color, in any of the forms "#RRGGBB", "#RGB",
"RRGGBB" or "RGB".
my $c1 = Imager::Color->new(web=>'#FFC0C0'); # pale red
• "gray" or "grey" which specifies a single channel, from 0 to 255.
# exactly the same
my $c1 = Imager::Color->new(gray=>128);
my $c1 = Imager::Color->new(grey=>128);
• "rgb" which takes a 3 member arrayref, containing each of the red, green and blue values.
# the same
my $c1 = Imager::Color->new(rgb=>[255, 100, 0]);
my $c1 = Imager::Color->new(r=>255, g=>100, b=>0);
• "hsv" which takes a 3 member arrayref, containing each of hue, saturation and value.
# the same
my $c1 = Imager::Color->new(hsv=>[120, 0.5, 1]);
my $c1 = Imager::Color->new(hue=>120, v=>1, s=>0.5);
• "gimp" which specifies a color from a GIMP palette file. You can specify the file name of the
palette file with the 'palette' parameter, or let Imager::Color look in various places, typically
"$HOME/gimp-1.x/palettes/Named_Colors" with and without the version number, and in
"/usr/share/gimp/palettes/". The palette file must have color names.
my $c1 = Imager::Color->new(gimp=>'snow');
my $c1 = Imager::Color->new(gimp=>'snow', palette=>'testimg/test_gimp_pal);
• "xname" which specifies a color from an X11 "rgb.txt" file. You can specify the file name of the
"rgb.txt" file with the "palette" parameter, or let Imager::Color look in various places, typically
"/usr/lib/X11/rgb.txt".
my $c1 = Imager::Color->new(xname=>'blue') # usually RGB(0, 0, 255)
• "builtin" which specifies a color from the built-in color table in Imager::Color::Table. The colors
in this module are the same as the default X11 "rgb.txt" file.
my $c1 = Imager::Color->new(builtin=>'black') # always RGB(0, 0, 0)
• "name" which specifies a name from either a GIMP palette, an X "rgb.txt" file or the built-in color
table, whichever is found first.
• 'channel0', 'channel1', etc, each of which specifies a single channel. These can be abbreviated to
'c0', 'c1' etc.
• 'channels' which takes an arrayref of the channel values.
Optionally you can add an alpha channel to a color with the 'alpha' or 'a' parameter.
These color specifications can be used for both constructing new colors with the new() method and
modifying existing colors with the set() method.
METHODS
hsv()
my($h, $s, $v, $alpha) = $color->hsv();
Returns the color as a Hue/Saturation/Value/Alpha tuple.
red
green
blue
alpha
Returns the respective component as an integer from 0 to 255.
as_float
Returns the color as a Imager::Color::Float object.
as_css_rgb
Returns the color as a CSS rgb() format color. This is always returned in the byte form, eg. rgb(255
128 64).
If the alpha is not full coverage (255) it will be rounded if the result of converting the color back
to an 8 bit color would return the same alpha, eg. if the color alpha is 128, it will be formatted as
0.5, not as the more precise 50.2%.
AUTHOR
Arnar M. Hrafnkelsson, addi@umich.edu And a great deal of help from others - see the "README" for a complete list.
SEE ALSO
Imager(3), Imager::Color http://imager.perl.org/