Class: Abachrome::Converters::LrgbToOklab

Inherits:
Base
  • Object
show all
Defined in:
lib/abachrome/converters/lrgb_to_oklab.rb

Instance Attribute Summary

Attributes inherited from Base

#from_space, #to_space

Class Method Summary collapse

Methods inherited from Base

#can_convert?, #convert, find_converter, #initialize, raise_unless, register

Constructor Details

This class inherits a constructor from Abachrome::Converters::Base

Class Method Details

.convert(rgb_color) ⇒ Abachrome::Color

Converts a color from linear RGB (LRGB) color space to OKLAB color space.

This conversion applies a matrix transformation to the linear RGB values, followed by a non-linear transformation, then another matrix transformation to produce OKLAB coordinates.

Parameters:

Returns:

  • (Abachrome::Color) —

    The converted color in OKLAB color space with the same alpha value as the input

Raises:

  • (ArgumentError) —

    If the provided color is not in LRGB color space



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# File 'lib/abachrome/converters/lrgb_to_oklab.rb', line 32

def self.convert(rgb_color)
  raise_unless rgb_color, :lrgb

  r, g, b = rgb_color.coordinates.map { |_| AbcDecimal(_) }

  l = (AD("0.41222147079999993") * r) + (AD("0.5363325363") * g) + (AD("0.0514459929") * b)
  m = (AD("0.2119034981999999") * r) + (AD("0.680699545099999") * g) + (AD("0.1073969566") * b)
  s = (AD("0.08830246189999998") * r) + (AD("0.2817188376") * g) + (AD("0.6299787005000002") * b)

  l_ = AbcDecimal(l)**Rational(1, 3)
  m_ = AbcDecimal(m)**Rational(1, 3)
  s_ = AbcDecimal(s)**Rational(1, 3)

  lightness = (AD("0.2104542553") * l_) + (AD("0.793617785") * m_) - (AD("0.0040720468") * s_)
  a         = (AD("1.9779984951") * l_) - (AD("2.4285922050") * m_) + (AD("0.4505937099") * s_)
  b         = (AD("0.0259040371") * l_) + (AD("0.7827717662") * m_) - (AD("0.8086757660") * s_)

  Color.new(ColorSpace.find(:oklab), [lightness, a, b], rgb_color.alpha)
end