Class: IsDark

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

Constant Summary collapse

BLUE_LUMINANCE_COEFFICIENT = 
0.0722
GREEN_LUMINANCE_COEFFICIENT = 
0.7152
HIGH_LUMINANCE_DIVIDER = 
1.055
HIGH_LUMINANCE_POWER = 
2.4
LOW_LUMINANCE_DIVIDER = 
12.92
LUMINANCE_THRESHOLD = 
0.05
MAXIMUM_COLOR_DEPTH = 
255
MAX_COLOR_VALUE_MULTIPLIER = 
655
MAX_COLOR_VALUE = 
MAX_COLOR_VALUE_MULTIPLIER * MAXIMUM_COLOR_DEPTH
LINEAR_LUMINANCE_THRESHOLD = 
(1 / (LOW_LUMINANCE_DIVIDER * 100.0)) * MAXIMUM_COLOR_DEPTH
NONLINEAR_TRANSFORM_DIVIDER = 
1.055
NONLINEAR_TRANSFORM_OFFSET = 
0.055
RED_LUMINANCE_COEFFICIENT = 
0.2126

Class Method Summary collapse

Class Method Details

.color(hex) ⇒ Object 



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# File 'lib/is_dark.rb', line 27

def self.color(hex)
  @r, @g, @b = hex.match(/^#(..)(..)(..)$/).captures.map(&:hex)
  @colorset = MAXIMUM_COLOR_DEPTH
  is_dark
end

.draw_debug_files(image, x, y, oldx, oldy) ⇒ Object 



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# File 'lib/is_dark.rb', line 97

def self.draw_debug_files(image, x, y, oldx, oldy)
  return unless oldx && oldy

  gc = Magick::Draw.new
  gc.line(x, y, oldx, oldy)
  gc.stroke('black')
  gc.draw(image)
  image.write(@debug_file_path)
end

.is_dark(x = nil, y = nil, set_not_detected_light = true) ⇒ Object

detects a dark color based on luminance W3 standarts ( www.w3.org/TR/WCAG20/#relativeluminancedef )



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# File 'lib/is_dark.rb', line 108

def self.is_dark(x = nil, y = nil, set_not_detected_light = true)
  dark = false
  inverted = false
  pixel = [@r.to_f, @g.to_f, @b.to_f]
  return true if pixel == [0.00, 0.00, 0.00] #hardcoded exception
  # probably not detected pixel color by Imagick, will be considered as "white" if "set_not_detected_light = true"
  if set_not_detected_light && pixel[0] == 0.0 && pixel[1] == 0.0 && pixel[2] == 0.0
    pixel = [MAXIMUM_COLOR_DEPTH, MAXIMUM_COLOR_DEPTH, MAXIMUM_COLOR_DEPTH]
    inverted = true
  end
  calculated = []
  pixel.each do |color|
    color /= @colorset
    if color <= LINEAR_LUMINANCE_THRESHOLD
      color /= LOW_LUMINANCE_DIVIDER
    else
      color = ((color + NONLINEAR_TRANSFORM_OFFSET) / NONLINEAR_TRANSFORM_DIVIDER)**HIGH_LUMINANCE_POWER
    end
    calculated << color
  end
  l = RED_LUMINANCE_COEFFICIENT * calculated[0] +
      GREEN_LUMINANCE_COEFFICIENT * calculated[1] +
      BLUE_LUMINANCE_COEFFICIENT * calculated[2]
  dark = true if l <= LUMINANCE_THRESHOLD
  if @with_debug
    debug = { 'X': x, 'Y': y, 'R': @r, 'G': @g, 'B': @b, 'luminance value': l, 'is_dark': dark,
              'inverted to white': inverted }
    p debug
  end
  dark
end

.magick_area_from_blob(x, y, blob, height, width, percent = 80, range = (0..10), set_not_detected_light = true) ⇒ Object

(x, y) is the left corner of an element over a blob, height and width is the element’s size



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# File 'lib/is_dark.rb', line 48

def self.magick_area_from_blob(x, y, blob, height, width, percent = 80, range = (0..10), set_not_detected_light = true)
  @set_not_detected_light = set_not_detected_light
  image = Magick::Image.read(blob).first
  dark = false
  dots = []
  range.each do |xx|
    range.each do |yy|
      dots << { 'x': (x + width * xx / 10).to_i, 'y': (y + height * yy / 10).to_i }
    end
  end

  points = 0
  if @with_debug_file
    oldx = false
    oldy = false
  end
  p '====================================================================' if @with_debug
  dots.each do |dot|
    x = dot[:x].to_i
    y = dot[:y].to_i
    pix = image.pixel_color(x, y)
    l = magick_pixel(pix, x, y, set_not_detected_light)
    points += 1 if l
    next unless @with_debug_file

    draw_debug_files(image, x, y, oldx, oldy)
    oldy = y
    oldx = x
  end
  dark = true if points >= (dots.length / 100) * percent
  if @with_debug
    p '===================================================================='
    p "Total Points: #{dots.length}, dark points amount:#{points}"
    p "Is \"invert to white not detectd pixels\" option enabled?:#{set_not_detected_light}"
    p "Signature will be inverted if #{percent}% of dots will be dark"
    p "Is inverted?: #{dark}"
    p '===================================================================='
  end
  dark
end

.magick_pixel(pix, x = nil, y = nil, set_not_detected_light = true) ⇒ Object 



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# File 'lib/is_dark.rb', line 33

def self.magick_pixel(pix, x = nil, y = nil, set_not_detected_light = true)
  @r = pix.red.to_f
  @g = pix.green.to_f
  @b = pix.blue.to_f
  @colorset = MAX_COLOR_VALUE
  is_dark(x, y, set_not_detected_light)
end

.magick_pixel_from_blob(x, y, blob, _set_not_detected_light = true) ⇒ Object 



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# File 'lib/is_dark.rb', line 41

def self.magick_pixel_from_blob(x, y, blob, _set_not_detected_light = true)
  image = Magick::Image.read(blob).first
  pix = image.pixel_color(x, y)
  magick_pixel(pix, x, y)
end

.set_debug_data(show_info = false, draw_file = false) ⇒ Object 



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# File 'lib/is_dark.rb', line 89

def self.set_debug_data(show_info = false, draw_file = false)
  @with_debug = show_info
  return unless draw_file != false

  @with_debug_file = true
  @debug_file_path = draw_file
end