Module: Abachrome::ColorMixins::ToGrayscale

Defined in:
lib/abachrome/color_mixins/to_grayscale.rb

Instance Method Summary collapse

Instance Method Details

#luma ⇒ AbcDecimal

Calculates the relative luminance using the default Rec. 601 standard. Alias for luma_601.

Returns:



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# File 'lib/abachrome/color_mixins/to_grayscale.rb', line 82

def luma
  luma_601
end

#luma_601 ⇒ AbcDecimal

Calculates the relative luminance (luma) value using Rec. 601 coefficients. This returns just the Y component without creating a new color.

Returns:



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# File 'lib/abachrome/color_mixins/to_grayscale.rb', line 62

def luma_601
  rgb_color = to_srgb
  r, g, b = rgb_color.coordinates
  (AD("0.299") * r) + (AD("0.587") * g) + (AD("0.114") * b)
end

#luma_709 ⇒ AbcDecimal

Calculates the relative luminance (luma) value using Rec. 709 coefficients. This returns just the Y component without creating a new color.

Returns:



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# File 'lib/abachrome/color_mixins/to_grayscale.rb', line 72

def luma_709
  rgb_color = to_srgb
  r, g, b = rgb_color.coordinates
  (AD("0.2126") * r) + (AD("0.7152") * g) + (AD("0.0722") * b)
end

#to_grayscale ⇒ Abachrome::Color

Converts the color to grayscale using the default Rec. 601 standard. This is an alias for to_grayscale_601 and matches the legacy behavior expected by most image processing applications.

Returns:



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# File 'lib/abachrome/color_mixins/to_grayscale.rb', line 54

def to_grayscale
  to_grayscale_601
end

#to_grayscale_601 ⇒ Abachrome::Color

Converts the color to grayscale using Rec. 601 luma coefficients (legacy NTSC standard). This is the same calculation used in the YIQ color space's Y component.

Returns:



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# File 'lib/abachrome/color_mixins/to_grayscale.rb', line 26

def to_grayscale_601
  rgb_color = to_srgb
  r, g, b = rgb_color.coordinates

  # Rec. 601 luma: Y = 0.299R + 0.587G + 0.114B
  luma = (AD("0.299") * r) + (AD("0.587") * g) + (AD("0.114") * b)

  Color.from_rgb(luma, luma, luma, alpha)
end

#to_grayscale_709 ⇒ Abachrome::Color

Converts the color to grayscale using Rec. 709 luma coefficients (HDTV standard).

Returns:



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# File 'lib/abachrome/color_mixins/to_grayscale.rb', line 39

def to_grayscale_709
  rgb_color = to_srgb
  r, g, b = rgb_color.coordinates

  # Rec. 709 luma: Y = 0.2126R + 0.7152G + 0.0722B
  luma = (AD("0.2126") * r) + (AD("0.7152") * g) + (AD("0.0722") * b)

  Color.from_rgb(luma, luma, luma, alpha)
end