Class: Abachrome::Converters::LmsToLrgb

Inherits:
Base
  • Object
show all
Defined in:
lib/abachrome/converters/lms_to_lrgb.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(lms_color) ⇒ Abachrome::Color

Converts a color from LMS color space to linear RGB color space.

This method implements the final part of the OKLAB to linear RGB transformation, converting LMS (Long, Medium, Short) coordinates to linear RGB coordinates using the standard transformation matrix. The LMS color space represents the response of the three types of cone cells in the human eye.

the same alpha as the input color

Raises:

  • (ArgumentError) —

    If the input color is not in LMS color space



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# File 'lib/abachrome/converters/lms_to_lrgb.rb', line 15

def self.convert(lms_color)
  raise_unless lms_color, :lms

  l, m, s = lms_color.coordinates.map { |_| AbcDecimal(_) }

  r = (l * AD("4.07674166134799")) +
      (m * AD("-3.307711590408193")) +
      (s * AD("0.230969928729428"))
  g = (l * AD("-1.2684380040921763")) +
      (m * AD("2.6097574006633715")) +
      (s * AD("-0.3413193963102197"))
  b = (l * AD("-0.004196086541837188")) +
      (m * AD("-0.7034186144594493")) +
      (s * AD("1.7076147009309444"))

  output_coords = [r, g, b].map { |it| [it, 0].max }

  Color.new(ColorSpace.find(:lrgb), output_coords, lms_color.alpha)
end