Class: PSD::Color

Inherits:
Object
  • Object
show all
Defined in:
lib/psd/color.rb

Overview

Various color conversion methods. All color values are stored in the PSD document in the color space as defined by the user instead of a normalized value of some kind. This means that we have to do all the conversion ourselves for each color space.

Class Method Summary collapse

Class Method Details

.ahsb_to_color(alpha, hue, saturation, brightness) ⇒ Object 



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# File 'lib/psd/color.rb', line 50

def self.ahsb_to_color(alpha, hue, saturation, brightness)
  if saturation == 0.0
    b = g = r = (255 * brightness).to_i
  else
    if brightness <= 0.5
      m2 = brightness * (1 + saturation)
    else
      m2 = brightness + saturation - brightness * saturation
    end

    m1 = 2 * brightness - m2
    r = hue_to_color(hue + 120, m1, m2)
    g = hue_to_color(hue, m1, m2)
    b = hue_to_color(hue - 120, m1, m2)
  end

  argb_to_color alpha, r, g, b
end

.alab_to_color(alpha, l, a, b) ⇒ Object 



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# File 'lib/psd/color.rb', line 100

def self.alab_to_color(alpha, l, a, b)
  xyz = lab_to_xyz(l, a, b)
  axyz_to_color alpha, xyz[:x], xyz[:y], xyz[:z]
end

.argb_to_color(a, r, g, b) ⇒ Object 



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# File 'lib/psd/color.rb', line 42

def self.argb_to_color(a, r, g, b)
  (a << 24) | (r << 16) | (g << 8) | b
end

.cmyk_to_color(c, m, y, k) ⇒ Object 



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# File 'lib/psd/color.rb', line 84

def self.cmyk_to_color(c, m, y, k)
  r = 1 - (c * (1 - k) + k) * 255
  g = 1 - (m * (1 - k) + k) * 255
  b = 1 - (y * (1 - k) + k) * 255

  r = [0, r, 255].sort[1]
  g = [0, g, 255].sort[1]
  b = [0, b, 255].sort[1]

  rgb_to_color r, g, b
end

.cmyk_to_rgb(c, m, y, k) ⇒ Object 



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# File 'lib/psd/color.rb', line 115

def self.cmyk_to_rgb(c, m, y, k)
  Hash[{
    r: (65535 - (c * (255 - k) + (k << 8))) >> 8,
    g: (65535 - (m * (255 - k) + (k << 8))) >> 8,
    b: (65535 - (y * (255 - k) + (k << 8))) >> 8
  }.map { |k, v| [k, Util.clamp(v, 0, 255)] }]
end

.color_space_to_argb(color_space, color_component) ⇒ Object

This is a relic of libpsd that will likely go away in a future version. It stored the entire color value in a 32-bit address space for speed.



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# File 'lib/psd/color.rb', line 9

def self.color_space_to_argb(color_space, color_component)
  color = case color_space
  when 0
    rgb_to_color *color_component
  when 1
    hsb_to_color color_component[0], 
      color_component[1] / 100.0, color_component[2] / 100.0
  when 2
    cmyk_to_color color_component[0] / 100.0,
      color_component[1] / 100.0, color_component[2] / 100.0,
      color_component[3] / 100.0
  when 7
    lab_to_color *color_component
  else
    0x00FFFFFF
  end

  color_to_argb(color)
end

.color_to_argb(color) ⇒ Object 



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# File 'lib/psd/color.rb', line 29

def self.color_to_argb(color)
  [
    (color) >> 24,
    ((color) & 0x00FF0000) >> 16,
    ((color) & 0x0000FF00) >> 8,
    (color) & 0x000000FF
  ]
end

.hsb_to_color(*args) ⇒ Object 



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# File 'lib/psd/color.rb', line 46

def self.hsb_to_color(*args)
  ahsb_to_color(255, *args)
end

.hue_to_color(hue, m1, m2) ⇒ Object 



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# File 'lib/psd/color.rb', line 69

def self.hue_to_color(hue, m1, m2)
  hue = (hue % 360).to_i
  if hue < 60
    v = m1 + (m2 - m1) * hue / 60
  elsif hue < 180
    v = m2
  elsif hue < 240
    v = m1 + (m2 - m1) * (240 - hue) / 60
  else
    v = m1
  end

  (v * 255).to_i
end

.lab_to_color(*args) ⇒ Object 



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# File 'lib/psd/color.rb', line 96

def self.lab_to_color(*args)
  alab_to_color(255, *args)
end

.lab_to_xyz(l, a, b) ⇒ Object 



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# File 'lib/psd/color.rb', line 105

def self.lab_to_xyz(l, a, b)
  y = (l + 16) / 116
  x = y + (a / 500)
  z = y - (b / 200)

  x, y, z = [x, y, z].map do |n|
    n**3 > 0.008856 ? n**3 : (n - 16 / 116) / 7.787
  end
end

.rgb_to_color(*args) ⇒ Object 



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# File 'lib/psd/color.rb', line 38

def self.rgb_to_color(*args)
  argb_to_color(255, *args)
end