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Man Pages


Manual Reference Pages  -  CONVERT::COLOR::RGB (3)

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NAME

"Convert::Color::RGB" - a color value represented as red/green/blue

CONTENTS

SYNOPSIS

Directly:



 use Convert::Color::RGB;

 my $red = Convert::Color::RGB->new( 1, 0, 0 );

 # Can also parse strings
 my $pink = Convert::Color::RGB->new( 1,0.7,0.7 );



Via Convert::Color:



 use Convert::Color;

 my $cyan = Convert::Color->new( rgb:0,1,1 );



DESCRIPTION

Objects in this class represent a color in RGB space, as a set of three floating-point values in the range 0 to 1.

For representations using 8- or 16-bit integers, see Convert::Color::RGB8 and Convert::Color::RGB16.

CONSTRUCTOR

CW$color = Convert::Color::RGB->new( CW$red, CW$green, CW$blue )

Returns a new object to represent the set of values given. These values should be floating-point numbers between 0 and 1. Values outside of this range will be clamped.

CW$color = Convert::Color::RGB->new( CW$string )

Parses $string for values, and construct a new object similar to the above three-argument form. The string should be in the form



 red,green,blue



containing the three floating-point values in decimal notation.

METHODS

CW$r = CW$color->red

CW$g = CW$color->green

CW$b = CW$color->blue

Accessors for the three components of the color.

( CW$red, CW$green, CW$blue ) = CW$color->rgb

Returns the individual red, green and blue color components of the color value.

CW$mix = CW$color->alpha_blend( CW$other, [ CW$alpha ] )

Return a new color which is a blended combination of the two passed into it. The optional $alpha parameter defines the mix ratio between the two colors, defaulting to 0.5 if not defined. Values closer to 0 will blend more of $color, closer to 1 will blend more of $other.

CW$measure = CW$color->dst_rgb( CW$other )

Return a measure of the distance between the two colors. This is the unweighted Euclidean distance of the three color components. Two identical colors will have a measure of 0, pure black and pure white have a distance of 1, and all others will lie somewhere inbetween.

CW$measure = CW$color->dst_rgb_cheap( CW$other )

Return a measure of the distance between the two colors. This is the sum of the squares of the differences of each of the color components. This is part of the value used to calculate dst_rgb, but since it involves no square root it will be cheaper to calculate, for use in cases where only the relative values matter, such as when picking the best match out of a set of colors. It ranges between 0 for identical colours and 3 for the distance between pure black and pure white.

EXAMPLES

    Generating Gradients

The alpha_blend method can be used to generate a smooth gradient between two colours.



 use Convert::Color;

 my $blue = Convert::Color->new("vga:blue");
 my $cyan = Convert::Color->new("vga:cyan");

 say $blue->alpha_blend( $cyan, $_/10 )->as_rgb8->hex for 0 .. 10



SEE ALSO

o Convert::Color - color space conversions
o Convert::Color::HSV - a color value represented as hue/saturation/value
o Convert::Color::HSL - a color value represented as hue/saturation/lightness

AUTHOR

Paul Evans <leonerd@leonerd.org.uk>
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perl v5.20.3 CONVERT::COLOR::RGB (3) 2014-06-01

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