Imager::Color(3) User Contributed Perl Documentation Imager::Color(3)NAMEImager::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:
· 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 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 $c1 = Imager::Color->new(builtin=>'black') # always RGB(0, 0, 0)
· "name" which specifies a name from either a GIMP palette, an X
"rgb.txt" file or the built-in color table, whichever is found
first.
· 'channel0', 'channel1', etc, each of which specifies a single
channel. These can be abbreviated to 'c0', 'c1' etc.
· 'channels' which takes an arrayref of the channel values.
Optionally you can add an alpha channel to a color with the 'alpha' or
'a' parameter.
These color specifications can be used for both constructing new colors
with the new() method and modifying existing colors with the set()
method.
METHODShsv()
my($h, $s, $v, $alpha) = $color->hsv();
Returns the color as a Hue/Saturation/Value/Alpha tuple.
AUTHOR
Arnar M. Hrafnkelsson, addi@umich.edu And a great deal of help from
others - see the "README" for a complete list.
SEE ALSOImager(3), Imager::Color http://imager.perl.org/
perl v5.14.3 2012-09-28 Imager::Color(3)
