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. Ifignore_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 Xrgb.txt
is found first. The same as using thename
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
andvalue
, optionally shortened toh
,s
andv
, 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
orRGB
.my $c1 = Imager::Color->new(web=>'#FFC0C0'); # pale red
gray
orgrey
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 X11rgb.txt
file. You can specify the file name of thergb.txt
file with thepalette
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 X11rgb.txt
file.my $c1 = Imager::Color->new(builtin=>'black') # always RGB(0, 0, 0)
name
which specifies a name from either a GIMP palette, an Xrgb.txt
file or the built-in color table, whichever is found first.'channel0', 'channel1', etc, each of which specifies a single channel. These can be abbreviated to 'c0', 'c1' etc.
'channels' which takes an arrayref of the channel values.
Optionally you can add an alpha channel to a color with the 'alpha' or 'a' parameter.
These color specifications can be used for both constructing new colors with the new() method and modifying existing colors with the set() method.
METHODS
- hsv()
-
my($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.
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/