Class: Color::XYZ

Inherits:
Base
  • Object
show all
Defined in:
lib/quadtone/color/xyz.rb

Instance Attribute Summary

Attributes inherited from Base

#components

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Base

#<=>, average, colorspace_name, #eql?, from_cgats, #hash, #initialize, num_components, #to_s, #to_str

Methods included from Math

#deg2rad, #rad2deg

Constructor Details

This class inherits a constructor from Color::Base

Class Method Details

.cgats_fields ⇒ Object 



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# File 'lib/quadtone/color/xyz.rb', line 14

def self.cgats_fields
  %w{XYZ_X XYZ_Y XYZ_Z}
end

.component_names ⇒ Object 



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# File 'lib/quadtone/color/xyz.rb', line 10

def self.component_names
  [:x, :y, :z]
end

.standard_reference ⇒ Object

Observer= 2°, Illuminant= D65



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# File 'lib/quadtone/color/xyz.rb', line 6

def self.standard_reference
  @@reference ||= new([95.047, 100.000, 108.883])
end

Instance Method Details

#to_cgats ⇒ Object 



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# File 'lib/quadtone/color/xyz.rb', line 70

def to_cgats
  {
    'XYZ_X' => x,
    'XYZ_Y' => y,
    'XYZ_Z' => z,
  }
end

#to_lab ⇒ Object 



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# File 'lib/quadtone/color/xyz.rb', line 30

def to_lab
  # http://www.easyrgb.com/index.php?X=MATH&H=07#text7

  ref = self.class.standard_reference

  x = self.x / ref.x
  y = self.y / ref.y
  z = self.z / ref.z

  x, y, z = [x, y, z].map do |n|
    if n > 0.008856
      n ** (1.0 / 3)
    else
      (7.787 * n) + (16 / 116)
    end
  end

  l = (116 * y) - 16
  a = 500 * (x - y)
  b = 200 * (y - z)

  Color::Lab.new([l, a, b])
end

#to_rgb ⇒ Object 



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# File 'lib/quadtone/color/xyz.rb', line 54

def to_rgb
  rgb = [
    (x *  3.2406) + (y * -1.5372) + (z * -0.4986),
    (x * -0.9689) + (y *  1.8758) + (z *  0.0415),
    (x *  0.0557) + (y * -0.2040) + (z *  1.0570),
  ]
  rgb = rgb.map do |n|
    if n > 0.0031308
      1.055 * (n ** (1 / 2.4)) - 0.055
    else
      12.92 * rgb[0]
    end
  end
  Color::RGB.new(rgb)
end

#x ⇒ Object 



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# File 'lib/quadtone/color/xyz.rb', line 18

def x
  @components[0]
end

#y ⇒ Object 



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# File 'lib/quadtone/color/xyz.rb', line 22

def y
  @components[1]
end

#z ⇒ Object 



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# File 'lib/quadtone/color/xyz.rb', line 26

def z
  @components[2]
end