Class: Quadtone::Curve

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

Constant Summary collapse

DeltaETolerance = 
1.0
DeltaEMethod = 
:density

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(params = {}) ⇒ Curve

Returns a new instance of Curve.



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# File 'lib/quadtone/curve.rb', line 11

def initialize(params={})
  params.each { |key, value| send("#{key}=", value) }
end

Instance Attribute Details

#channel ⇒ Object

Returns the value of attribute channel.



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# File 'lib/quadtone/curve.rb', line 8

def channel
  @channel
end

#samples ⇒ Object

Returns the value of attribute samples.



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# File 'lib/quadtone/curve.rb', line 9

def samples
  @samples
end

Instance Method Details

#dmax ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 82

def dmax
  @samples.last.output_value
end

#dmin ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 78

def dmin
  @samples.first.output_value
end

#draw_svg(svg, options = {}) ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 90

def draw_svg(svg, options={})
  size = options[:size] || 500

  # draw interpolated curve
  svg.g(fill: 'none', stroke: 'green', :'stroke-width' => 1) do
    samples = (0..1).step(1.0 / size).map do |n|
      [size * n, size * output_for_input(n)]
    end
    svg.polyline(points: samples.map { |pt| pt.join(',') }.join(' '))
  end

  # draw markers for ink limits
  {
    density: 'gray',
    # cie76: 'red',
    # cie94: 'green',
    # cmclc: 'blue',
  }.each do |method, color|
    limit = ink_limit(method)
    x, y = size * limit.input_value, size * limit.output_value
    svg.g(stroke: color, :'stroke-width' => 3) do
      svg.line(x1: x, y1: y + 8, x2: x, y2: y - 8)
    end
  end

  # if (limit = ink_limit)
  #   x, y = size * limit.input_value, size * limit.output_value
  #   svg.g(stroke: 'black', :'stroke-width' => 3) do
  #     svg.line(x1: x, y1: y + 15, x2: x, y2: y - 15)
  #   end
  # end

  # draw individual samples
  @samples.each_with_index do |sample, i|
    svg.circle(
      cx: size * sample.input_value,
      cy: size * sample.output_value,
      r: 3,
      stroke: 'none',
      fill: "rgb(#{sample.output.to_rgb.to_a.join(',')})",
      title: sample.label)
  end

  svg.target!
end

#dynamic_range ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 86

def dynamic_range
  [dmin, dmax]
end

#grayscale(steps) ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 33

def grayscale(steps)
  spliner = Spliner::Spliner.new(Hash[ @samples.map { |s| [s.input.value, s.output.l] } ])
  scale = (0 .. 1).step(1.0 / (steps - 1))
  spliner[scale].map { |l| Color::Lab.new([l]) }
end

#ink_limit(method = DeltaEMethod) ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 39

def ink_limit(method=DeltaEMethod)
  # ;;@samples.each { |s| warn "%s-%s: %.2f => %.2f" % [@channel, s.id, s.input.value, s.output.value] }
  @samples.each_with_index do |sample, i|
    if i > 0
      previous_sample = @samples[i - 1]
      return previous_sample if sample.output_value < previous_sample.output_value
      return previous_sample if previous_sample.output.delta_e(sample.output, method) < DeltaETolerance
    end
  end
  @samples.last
end

#input_for_output(output) ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 24

def input_for_output(output)
  @input_spliner ||= Spliner::Spliner.new(@samples.map(&:output_value), @samples.map(&:input_value))
  @input_spliner[output]
end

#normalize_inputs ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 59

def normalize_inputs
  scale = 1 / @samples.last.input.value
  @samples.each do |sample|
    sample.input = Color::Gray.new(k: sample.input.k * scale)
  end
  @input_spliner = @output_spliner = nil
end

#num_samples ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 29

def num_samples
  @samples.length
end

#output_for_input(input) ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 19

def output_for_input(input)
  @output_spliner ||= Spliner::Spliner.new(@samples.map(&:input_value), @samples.map(&:output_value))
  @output_spliner[input]
end

#trim_to_limit ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 51

def trim_to_limit
  limit = ink_limit
  i = @samples.index(limit)
  ;;warn "trimming curve #{@channel} to sample \##{i}: #{limit}"
  @samples.slice!(i + 1 .. -1)
  @input_spliner = @output_spliner = nil
end

#verify_increasing_values ⇒ Object 



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# File 'lib/quadtone/curve.rb', line 67

def verify_increasing_values
  @samples.each_with_index do |sample, i|
    if i > 0
      previous_sample = @samples[i - 1]
      if sample.output_value < previous_sample.output_value
        raise "Samples not in increasing order (#{sample.label} [#{i}]: #{sample.output_value} < #{previous_sample.output_value})"
      end
    end
  end
end