text: # vim: set et sw=4 sts=4 fileencoding=utf-8:
  #
  # Python camera library for the Rasperry-Pi camera module
  # Copyright (c) 2013-2015 Dave Jones <dave@waveform.org.uk>
  #
  # Redistribution and use in source and binary forms, with or without
  # modification, are permitted provided that the following conditions are met:
  #
  #     * Redistributions of source code must retain the above copyright
  #       notice, this list of conditions and the following disclaimer.
  #     * Redistributions in binary form must reproduce the above copyright
  #       notice, this list of conditions and the following disclaimer in the
  #       documentation and/or other materials provided with the distribution.
  #     * Neither the name of the copyright holder nor the
  #       names of its contributors may be used to endorse or promote products
  #       derived from this software without specific prior written permission.
  #
  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  # AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  # IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  # ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
  # LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  # CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  # SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  # INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  # CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  # POSSIBILITY OF SUCH DAMAGE.
  
  """
  The color module defines a class for representing a color, along with various
  ancillary classes which can be used to manipulate aspects of a color.
  
  .. note::
  
      All classes in this module are available from the :mod:`picamera` namespace
      without having to import :mod:`picamera.color` directly.
  
  The following classes are defined in the module:
  
  
  Color
  =====
  
  .. autoclass:: Color
      :members:
  
  
  Red
  ===
  
  .. autoclass:: Red
      :members:
  
  
  Green
  =====
  
  .. autoclass:: Green
      :members:
  
  
  Blue
  ====
  
  .. autoclass:: Blue
      :members:
  
  
  Hue
  ===
  
  .. autoclass:: Hue
      :members:
  
  
  Saturation
  ==========
  
  .. autoclass:: Saturation
      :members:
  
  
  Lightness
  =========
  
  .. autoclass:: Lightness
      :members:
  
  """
  
  from __future__ import (
      unicode_literals,
      print_function,
      division,
      absolute_import,
      )
  
  # Make Py2's str and range equivalent to Py3's
  str = type('')
  
  
  import colorsys
  from math import pi
  from collections import namedtuple
  
  
  # From the CSS Color Module Level 3 specification, section 4.3
  # <http://www.w3.org/TR/css3-color/#svg-color>
  NAMED_COLORS = {
      'aliceblue':             '#f0f8ff',
      'antiquewhite':          '#faebd7',
      'aqua':                  '#00ffff',
      'aquamarine':            '#7fffd4',
      'azure':                 '#f0ffff',
      'beige':                 '#f5f5dc',
      'bisque':                '#ffe4c4',
      'black':                 '#000000',
      'blanchedalmond':        '#ffebcd',
      'blue':                  '#0000ff',
      'blueviolet':            '#8a2be2',
      'brown':                 '#a52a2a',
      'burlywood':             '#deb887',
      'cadetblue':             '#5f9ea0',
      'chartreuse':            '#7fff00',
      'chocolate':             '#d2691e',
      'coral':                 '#ff7f50',
      'cornflowerblue':        '#6495ed',
      'cornsilk':              '#fff8dc',
      'crimson':               '#dc143c',
      'cyan':                  '#00ffff',
      'darkblue':              '#00008b',
      'darkcyan':              '#008b8b',
      'darkgoldenrod':         '#b8860b',
      'darkgray':              '#a9a9a9',
      'darkgreen':             '#006400',
      'darkgrey':              '#a9a9a9',
      'darkkhaki':             '#bdb76b',
      'darkmagenta':           '#8b008b',
      'darkolivegreen':        '#556b2f',
      'darkorange':            '#ff8c00',
      'darkorchid':            '#9932cc',
      'darkred':               '#8b0000',
      'darksalmon':            '#e9967a',
      'darkseagreen':          '#8fbc8f',
      'darkslateblue':         '#483d8b',
      'darkslategray':         '#2f4f4f',
      'darkslategrey':         '#2f4f4f',
      'darkturquoise':         '#00ced1',
      'darkviolet':            '#9400d3',
      'deeppink':              '#ff1493',
      'deepskyblue':           '#00bfff',
      'dimgray':               '#696969',
      'dimgrey':               '#696969',
      'dodgerblue':            '#1e90ff',
      'firebrick':             '#b22222',
      'floralwhite':           '#fffaf0',
      'forestgreen':           '#228b22',
      'fuchsia':               '#ff00ff',
      'gainsboro':             '#dcdcdc',
      'ghostwhite':            '#f8f8ff',
      'gold':                  '#ffd700',
      'goldenrod':             '#daa520',
      'gray':                  '#808080',
      'green':                 '#008000',
      'greenyellow':           '#adff2f',
      'grey':                  '#808080',
      'honeydew':              '#f0fff0',
      'hotpink':               '#ff69b4',
      'indianred':             '#cd5c5c',
      'indigo':                '#4b0082',
      'ivory':                 '#fffff0',
      'khaki':                 '#f0e68c',
      'lavender':              '#e6e6fa',
      'lavenderblush':         '#fff0f5',
      'lawngreen':             '#7cfc00',
      'lemonchiffon':          '#fffacd',
      'lightblue':             '#add8e6',
      'lightcoral':            '#f08080',
      'lightcyan':             '#e0ffff',
      'lightgoldenrodyellow':  '#fafad2',
      'lightgray':             '#d3d3d3',
      'lightgreen':            '#90ee90',
      'lightgrey':             '#d3d3d3',
      'lightpink':             '#ffb6c1',
      'lightsalmon':           '#ffa07a',
      'lightseagreen':         '#20b2aa',
      'lightskyblue':          '#87cefa',
      'lightslategray':        '#778899',
      'lightslategrey':        '#778899',
      'lightsteelblue':        '#b0c4de',
      'lightyellow':           '#ffffe0',
      'lime':                  '#00ff00',
      'limegreen':             '#32cd32',
      'linen':                 '#faf0e6',
      'magenta':               '#ff00ff',
      'maroon':                '#800000',
      'mediumaquamarine':      '#66cdaa',
      'mediumblue':            '#0000cd',
      'mediumorchid':          '#ba55d3',
      'mediumpurple':          '#9370db',
      'mediumseagreen':        '#3cb371',
      'mediumslateblue':       '#7b68ee',
      'mediumspringgreen':     '#00fa9a',
      'mediumturquoise':       '#48d1cc',
      'mediumvioletred':       '#c71585',
      'midnightblue':          '#191970',
      'mintcream':             '#f5fffa',
      'mistyrose':             '#ffe4e1',
      'moccasin':              '#ffe4b5',
      'navajowhite':           '#ffdead',
      'navy':                  '#000080',
      'oldlace':               '#fdf5e6',
      'olive':                 '#808000',
      'olivedrab':             '#6b8e23',
      'orange':                '#ffa500',
      'orangered':             '#ff4500',
      'orchid':                '#da70d6',
      'palegoldenrod':         '#eee8aa',
      'palegreen':             '#98fb98',
      'paleturquoise':         '#afeeee',
      'palevioletred':         '#db7093',
      'papayawhip':            '#ffefd5',
      'peachpuff':             '#ffdab9',
      'peru':                  '#cd853f',
      'pink':                  '#ffc0cb',
      'plum':                  '#dda0dd',
      'powderblue':            '#b0e0e6',
      'purple':                '#800080',
      'red':                   '#ff0000',
      'rosybrown':             '#bc8f8f',
      'royalblue':             '#4169e1',
      'saddlebrown':           '#8b4513',
      'salmon':                '#fa8072',
      'sandybrown':            '#f4a460',
      'seagreen':              '#2e8b57',
      'seashell':              '#fff5ee',
      'sienna':                '#a0522d',
      'silver':                '#c0c0c0',
      'skyblue':               '#87ceeb',
      'slateblue':             '#6a5acd',
      'slategray':             '#708090',
      'slategrey':             '#708090',
      'snow':                  '#fffafa',
      'springgreen':           '#00ff7f',
      'steelblue':             '#4682b4',
      'tan':                   '#d2b48c',
      'teal':                  '#008080',
      'thistle':               '#d8bfd8',
      'tomato':                '#ff6347',
      'turquoise':             '#40e0d0',
      'violet':                '#ee82ee',
      'wheat':                 '#f5deb3',
      'white':                 '#ffffff',
      'whitesmoke':            '#f5f5f5',
      'yellow':                '#ffff00',
      'yellowgreen':           '#9acd32',
      }
  
  
  class Red(float):
      """
      Represents the red component of a :class:`Color` for use in
      transformations. Instances of this class can be constructed directly with a
      float value, or by querying the :attr:`Color.red` attribute. Addition,
      subtraction, and multiplication are supported with :class:`Color`
      instances. For example::
  
          >>> Color.from_rgb(0, 0, 0) + Red(0.5)
          <Color "#7f0000">
          >>> Color('#f00') - Color('#900').red
          <Color "#660000">
          >>> (Red(0.1) * Color('red')).red
          Red(0.1)
      """
  
      def __repr__(self):
          return "Red(%s)" % self
  
  
  class Green(float):
      """
      Represents the green component of a :class:`Color` for use in
      transformations.  Instances of this class can be constructed directly with
      a float value, or by querying the :attr:`Color.green` attribute. Addition,
      subtraction, and multiplication are supported with :class:`Color`
      instances. For example::
  
          >>> Color(0, 0, 0) + Green(0.1)
          <Color "#001900">
          >>> Color.from_yuv(1, -0.4, -0.6) - Green(1)
          <Color "#50002f">
          >>> (Green(0.5) * Color('white')).rgb
          (Red(1.0), Green(0.5), Blue(1.0))
      """
  
      def __repr__(self):
          return "Green(%s)" % self
  
  
  class Blue(float):
      """
      Represents the blue component of a :class:`Color` for use in
      transformations.  Instances of this class can be constructed directly with
      a float value, or by querying the :attr:`Color.blue` attribute. Addition,
      subtraction, and multiplication are supported with :class:`Color`
      instances. For example::
  
          >>> Color(0, 0, 0) + Blue(0.2)
          <Color "#000033">
          >>> Color.from_hls(0.5, 0.5, 1.0) - Blue(1)
          <Color "#00fe00">
          >>> Blue(0.9) * Color('white')
          <Color "#ffffe5">
      """
  
      def __repr__(self):
          return "Blue(%s)" % self
  
  
  class Hue(float):
      """
      Represents the hue of a :class:`Color` for use in transformations.
      Instances of this class can be constructed directly with a float value in
      the range [0.0, 1.0) representing an angle around the `HSL hue wheel`_. As
      this is a circular mapping, 0.0 and 1.0 effectively mean the same thing,
      i.e.  out of range values will be normalized into the range [0.0, 1.0).
  
      The class can also be constructed with the keyword arguments ``deg`` or
      ``rad`` if you wish to specify the hue value in degrees or radians instead,
      respectively. Instances can also be constructed by querying the
      :attr:`Color.hue` attribute.
  
      Addition, subtraction, and multiplication are supported with :class:`Color`
      instances. For example::
  
          >>> Color(1, 0, 0).hls
          (0.0, 0.5, 1.0)
          >>> (Color(1, 0, 0) + Hue(deg=180)).hls
          (0.5, 0.5, 1.0)
  
      Note that whilst multiplication by a :class:`Hue` doesn't make much sense,
      it is still supported. However, the circular nature of a hue value can lead
      to suprising effects. In particular, since 1.0 is equivalent to 0.0 the
      following may be observed::
  
          >>> (Hue(1.0) * Color.from_hls(0.5, 0.5, 1.0)).hls
          (0.0, 0.5, 1.0)
  
      .. _HSL hue wheel: https://en.wikipedia.org/wiki/Hue
      """
  
      def __new__(cls, n=None, deg=None, rad=None):
          if n is not None:
              return super(Hue, cls).__new__(cls, n % 1.0)
          elif deg is not None:
              return super(Hue, cls).__new__(cls, (deg / 360.0) % 1.0)
          elif rad is not None:
              return super(Hue, cls).__new__(cls, (rad / (2 * pi)) % 1.0)
          else:
              raise ValueError('You must specify a value, or deg or rad')
  
      def __repr__(self):
          return "Hue(deg=%s)" % self.deg
  
      @property
      def deg(self):
          return self * 360.0
  
      @property
      def rad(self):
          return self * 2 * pi
  
  
  class Lightness(float):
      """
      Represents the lightness of a :class:`Color` for use in transformations.
      Instances of this class can be constructed directly with a float value, or
      by querying the :attr:`Color.lightness` attribute. Addition, subtraction,
      and multiplication are supported with :class:`Color` instances. For
      example::
  
          >>> Color(0, 0, 0) + Lightness(0.1)
          <Color "#191919">
          >>> Color.from_rgb_bytes(0x80, 0x80, 0) - Lightness(0.2)
          <Color "#191900">
          >>> Lightness(0.9) * Color('wheat')
          <Color "#f0cd8d">
      """
  
      def __repr__(self):
          return "Lightness(%s)" % self
  
  
  class Saturation(float):
      """
      Represents the saturation of a :class:`Color` for use in transformations.
      Instances of this class can be constructed directly with a float value, or
      by querying the :attr:`Color.saturation` attribute. Addition, subtraction,
      and multiplication are supported with :class:`Color` instances. For
      example::
  
          >>> Color(0.9, 0.9, 0.6) + Saturation(0.1)
          <Color "#ebeb92">
          >>> Color('red') - Saturation(1)
          <Color "#7f7f7f">
          >>> Saturation(0.5) * Color('wheat')
          <Color "#e4d9c3">
      """
  
      def __repr__(self):
          return "Lightness(%s)" % self
  
  
  
  clamp_float = lambda v: max(0.0, min(1.0, v))
  clamp_bytes = lambda v: max(0, min(255, v))
  
  class Color(namedtuple('Color', ('red', 'green', 'blue'))):
      """
      The Color class is a tuple which represents a color as red, green, and
      blue components.
  
      The class has a flexible constructor which allows you to create an instance
      from a variety of color systems including `RGB`_, `Y'UV`_, `Y'IQ`_, `HLS`_,
      and `HSV`_.  There are also explicit constructors for each of these systems
      to allow you to force the use of a system in your code. For example, an
      instance of :class:`Color` can be constructed in any of the following
      ways::
  
          >>> Color('#f00')
          <Color "#ff0000">
          >>> Color('green')
          <Color "#008000">
          >>> Color(0, 0, 1)
          <Color "#0000ff">
          >>> Color(hue=0, saturation=1, value=0.5)
          <Color "#7f0000">
          >>> Color(y=0.4, u=-0.05, v=0.615)
          <Color "#ff0f4c">
  
      The specific forms that the default constructor will accept are enumerated
      below:
  
      +------------------------------+------------------------------------------+
      | Style                        | Description                              |
      +==============================+==========================================+
      | Single positional parameter  | Equivalent to calling                    |
      |                              | :meth:`Color.from_string`.               |
      +------------------------------+------------------------------------------+
      | Three positional parameters  | Equivalent to calling                    |
      |                              | :meth:`Color.from_rgb` if all three      |
      |                              | parameters are between 0.0 and 1.0, or   |
      |                              | :meth:`Color.from_rgb_bytes` otherwise.  |
      +------------------------------+                                          |
      | Three named parameters,      |                                          |
      | "r", "g", "b"                |                                          |
      +------------------------------+                                          |
      | Three named parameters,      |                                          |
      | "red", "green", "blue"       |                                          |
      +------------------------------+------------------------------------------+
      | Three named parameters,      | Equivalent to calling                    |
      | "y", "u", "v"                | :meth:`Color.from_yuv` if "y" is between |
      |                              | 0.0 and 1.0, "u" is between -0.436 and   |
      |                              | 0.436, and "v" is between -0.615 and     |
      |                              | 0.615, or :meth:`Color.from_yuv_bytes`   |
      |                              | otherwise.                               |
      +------------------------------+------------------------------------------+
      | Three named parameters,      | Equivalent to calling                    |
      | "y", "i", "q"                | :meth:`Color.from_yiq`.                  |
      +------------------------------+------------------------------------------+
      | Three named parameters,      | Equivalent to calling                    |
      | "h", "l", "s"                | :meth:`Color.from_hls`.                  |
      +------------------------------+                                          |
      | Three named parameters,      |                                          |
      | "hue", "lightness",          |                                          |
      | "saturation"                 |                                          |
      +------------------------------+------------------------------------------+
      | Three named parameters       | Equivalent to calling                    |
      | "h", "s", "v"                | :meth:`Color.from_hsv`                   |
      +------------------------------+                                          |
      | Three named parameters       |                                          |
      | "hue", "saturation", "value" |                                          |
      +------------------------------+------------------------------------------+
  
      If the constructor parameters do not conform to any of the variants in the
      table above, a :exc:`ValueError` will be thrown.
  
      Internally, the color is *always* represented as 3 float values
      corresponding to the red, green, and blue components of the color. These
      values take a value from 0.0 to 1.0 (least to full intensity). The class
      provides several attributes which can be used to convert one color system
      into another::
  
          >>> Color('#f00').hls
          (0.0, 0.5, 1.0)
          >>> Color.from_string('green').hue
          Hue(deg=120.0)
          >>> Color.from_rgb_bytes(0, 0, 255).yuv
          (0.114, 0.435912, -0.099978)
  
      As :class:`Color` derives from tuple, instances are immutable. While this
      provides the advantage that they can be used as keys in a dict, it does
      mean that colors themselves cannot be directly manipulated (e.g. by
      reducing the red component).
  
      However, several auxilliary classes in the module provide the ability to
      perform simple transformations of colors via operators which produce a new
      :class:`Color` instance. For example::
  
          >>> Color('red') - Red(0.5)
          <Color "#7f0000">
          >>> Color('green') + Red(0.5)
          <Color "#7f8000">
          >>> Color.from_hls(0.5, 0.5, 1.0)
          <Color "#00feff">
          >>> Color.from_hls(0.5, 0.5, 1.0) * Lightness(0.8)
          <Color "#00cbcc">
          >>> (Color.from_hls(0.5, 0.5, 1.0) * Lightness(0.8)).hls
          (0.5, 0.4, 1.0)
  
      From the last example above one can see that even attributes not directly
      stored by the color (such as lightness) can be manipulated in this fashion.
      In this case a :class:`Color` instance is constructed from HLS (hue,
      lightness, saturation) values with a lightness of 0.5. This is multiplied
      by a :class:`Lightness` instance with a value of 0.8 which constructs a new
      :class:`Color` with the same hue and saturation, but a lightness of 0.5 *
      0.8 = 0.4.
  
      If an instance is converted to a string (with :func:`str`) it will return a
      string containing the 7-character HTML code for the color (e.g. "#ff0000"
      for red). As can be seen in the examples above, a similar representation is
      returned for :func:`repr`.
  
      .. _RGB: https://en.wikipedia.org/wiki/RGB_color_space
      .. _Y'UV: https://en.wikipedia.org/wiki/YUV
      .. _Y'IQ: https://en.wikipedia.org/wiki/YIQ
      .. _HLS: https://en.wikipedia.org/wiki/HSL_and_HSV
      .. _HSV: https://en.wikipedia.org/wiki/HSL_and_HSV
      """
  
      def __new__(cls, *args, **kwargs):
          def from_rgb(r, g, b):
              if 0.0 <= r <= 1.0 and 0.0 <= g <= 1.0 and 0.0 <= b <= 1.0:
                  return cls.from_rgb(r, g, b)
              else:
                  return cls.from_rgb_bytes(r, g, b)
  
          def from_yuv(y, u, v):
              if 0.0 <= y <= 1.0 and -0.436 <= u <= 0.436 and -0.615 <= v <= 0.615:
                  return cls.from_yuv(y, u, v)
              else:
                  return cls.from_yuv_bytes(y, u, v)
  
          if kwargs:
              try:
                  return {
                      frozenset('rgb'):   from_rgb,
                      frozenset('yuv'):   from_yuv,
                      frozenset('yiq'):   cls.from_yiq,
                      frozenset('hls'):   cls.from_hls,
                      frozenset('hsv'):   cls.from_hsv,
                      frozenset(('red', 'green', 'blue')):
                          lambda red, green, blue: from_rgb(red, green, blue),
                      frozenset(('hue', 'lightness', 'saturation')):
                          lambda hue, lightness, saturation: cls.from_hls(hue, lightness, saturation),
                      frozenset(('hue', 'saturation', 'value')):
                          lambda hue, saturation, value: cls.from_hsv(hue, saturation, value),
                      }[frozenset(kwargs.keys())](**kwargs)
              except KeyError:
                  pass
          else:
              if len(args) == 1:
                  return cls.from_string(args[0])
              elif len(args) == 3:
                  return from_rgb(*args)
          raise ValueError('Unable to construct Color from provided arguments')
  
      @classmethod
      def from_string(cls, s):
          """
          Construct a :class:`Color` from a 4 or 7 character CSS-like
          representation (e.g. "#f00" or "#ff0000" for red), or from one of the
          named colors (e.g. "green" or "wheat") from the `CSS standard`_. Any
          other string format will result in a :exc:`ValueError`.
  
          .. _CSS standard: http://www.w3.org/TR/css3-color/#svg-color
          """
          if isinstance(s, bytes):
              s = s.decode('ascii')
          if s.startswith('#'):
              if len(s) == 7:
                  return cls.from_rgb_bytes(
                      int(s[1:3], base=16),
                      int(s[3:5], base=16),
                      int(s[5:7], base=16)
                      )
              elif len(s) == 4:
                  return cls.from_rgb_bytes(
                      int(s[1:2], base=16) * 0x11,
                      int(s[2:3], base=16) * 0x11,
                      int(s[3:4], base=16) * 0x11
                      )
              raise ValueError('Unrecognized color format "%s"' % s)
          try:
              return cls.from_string(NAMED_COLORS[s.lower()])
          except KeyError:
              raise ValueError('Unrecognized color name "%s"' % s)
  
      @classmethod
      def from_rgb(cls, r, g, b):
          """
          Construct a :class:`Color` from three `RGB`_ float values between 0.0
          and 1.0.
          """
          return super(Color, cls).__new__(cls, r, g, b)
  
      @classmethod
      def from_rgb_bytes(cls, r, g, b):
          """
          Construct a :class:`Color` from three `RGB`_ byte values between 0 and
          255.
          """
          return super(Color, cls).__new__(cls, r / 255.0, g / 255.0, b / 255.0)
  
      @classmethod
      def from_yuv(cls, y, u, v):
          """
          Construct a :class:`Color` from three `Y'UV`_ float values. The Y value
          may be between 0.0 and 1.0. U may be between -0.436 and 0.436, while
          V may be between -0.615 and 0.615.
          """
          return super(Color, cls).__new__(
                  cls,
                  clamp_float(y + 1.14  * v),
                  clamp_float(y - 0.395 * u - 0.581 * v),
                  clamp_float(y + 2.033 * u),
                  )
  
      @classmethod
      def from_yuv_bytes(cls, y, u, v):
          """
          Construct a :class:`Color` from three `Y'UV`_ byte values between 0 and
          255. The U and V values are biased by 128 to prevent negative values as
          is typical in video applications. The Y value is biased by 16 for the
          same purpose.
          """
          c = y - 16
          d = u - 128
          e = v - 128
          return cls.from_rgb_bytes(
                  clamp_bytes((298 * c + 409 * e + 128) >> 8),
                  clamp_bytes((298 * c - 100 * d - 208 * e + 128) >> 8),
                  clamp_bytes((298 * c + 516 * d + 128) >> 8),
                  )
  
      @classmethod
      def from_yiq(cls, y, i, q):
          """
          Construct a :class:`Color` from three `Y'IQ`_ float values. Y' can be
          between 0.0 and 1.0, while I and Q can be between -1.0 and 1.0.
          """
          return super(Color, cls).__new__(cls, *colorsys.yiq_to_rgb(y, i, q))
  
      @classmethod
      def from_hls(cls, h, l, s):
          """
          Construct a :class:`Color` from `HLS`_ (hue, lightness, saturation)
          floats between 0.0 and 1.0.
          """
          return super(Color, cls).__new__(cls, *colorsys.hls_to_rgb(h, l, s))
  
      @classmethod
      def from_hsv(cls, h, s, v):
          """
          Construct a :class:`Color` from `HSV`_ (hue, saturation, value) floats
          between 0.0 and 1.0.
          """
          return super(Color, cls).__new__(cls, *colorsys.hsv_to_rgb(h, s, v))
  
      def __add__(self, other):
          if isinstance(other, Red):
              return Color(clamp_float(self.red + other), self.green, self.blue)
          elif isinstance(other, Green):
              return Color(self.red, clamp_float(self.green + other), self.blue)
          elif isinstance(other, Blue):
              return Color(self.red, self.green, clamp_float(self.blue + other))
          elif isinstance(other, Hue):
              h, l, s = self.hls
              return Color.from_hls((h + other) % 1.0, l, s)
          elif isinstance(other, Lightness):
              h, l, s = self.hls
              return Color.from_hls(h, clamp_float(l + other), s)
          elif isinstance(other, Saturation):
              h, l, s = self.hls
              return Color.from_hls(h, l, clamp_float(s + other))
          return NotImplemented
  
      def __radd__(self, other):
          # Addition is commutative
          if isinstance(other, (Red, Green, Blue, Hue, Lightness, Saturation)):
              return self.__add__(other)
          return NotImplemented
  
      def __sub__(self, other):
          if isinstance(other, Red):
              return Color(clamp_float(self.red - other), self.green, self.blue)
          elif isinstance(other, Green):
              return Color(self.red, clamp_float(self.green - other), self.blue)
          elif isinstance(other, Blue):
              return Color(self.red, self.green, clamp_float(self.blue - other))
          elif isinstance(other, Hue):
              h, l, s = self.hls
              return Color.from_hls((h - other) % 1.0, l, s)
          elif isinstance(other, Lightness):
              h, l, s = self.hls
              return Color.from_hls(h, clamp_float(l - other), s)
          elif isinstance(other, Saturation):
              h, l, s = self.hls
              return Color.from_hls(h, l, clamp_float(s - other))
          return NotImplemented
  
      def __rsub__(self, other):
          if isinstance(other, Red):
              return Color(clamp_float(other - self.red), self.green, self.blue)
          elif isinstance(other, Green):
              return Color(self.red, clamp_float(other - self.green), self.blue)
          elif isinstance(other, Blue):
              return Color(self.red, self.green, clamp_float(other - self.blue))
          elif isinstance(other, Hue):
              h, l, s = self.hls
              return Color.from_hls((other - h) % 1.0, l, s)
          elif isinstance(other, Lightness):
              h, l, s = self.hls
              return Color.from_hls(h, clamp_float(other - l), s)
          elif isinstance(other, Saturation):
              h, l, s = self.hls
              return Color.from_hls(h, l, clamp_float(other - s))
          return NotImplemented
  
      def __mul__(self, other):
          if isinstance(other, Red):
              return Color(clamp_float(self.red * other), self.green, self.blue)
          elif isinstance(other, Green):
              return Color(self.red, clamp_float(self.green * other), self.blue)
          elif isinstance(other, Blue):
              return Color(self.red, self.green, clamp_float(self.blue * other))
          elif isinstance(other, Hue):
              h, l, s = self.hls
              return Color.from_hls((h * other) % 1.0, l, s)
          elif isinstance(other, Lightness):
              h, l, s = self.hls
              return Color.from_hls(h, clamp_float(l * other), s)
          elif isinstance(other, Saturation):
              h, l, s = self.hls
              return Color.from_hls(h, l, clamp_float(s * other))
          return NotImplemented
  
      def __rmul__(self, other):
          # Multiplication is commutative
          if isinstance(other, (Red, Green, Blue, Hue, Lightness, Saturation)):
              return self.__mul__(other)
  
      def __str__(self):
          return '#%02x%02x%02x' % self.rgb_bytes
  
      def __repr__(self):
          return '<Color "%s">' % str(self)
  
      @property
      def rgb(self):
          """
          Returns a 3-tuple of (red, green, blue) float values (between 0.0 and
          1.0).
          """
          return (self.red, self.green, self.blue)
  
      @property
      def rgb_bytes(self):
          """
          Returns a 3-tuple of (red, green, blue) byte values.
          """
          return (
                  int(self.red * 255),
                  int(self.green * 255),
                  int(self.blue * 255),
                  )
  
      @property
      def yuv(self):
          """
          Returns a 3-tuple of (y, u, v) float values; y values can be between
          0.0 and 1.0, u values are between -0.436 and 0.436, and v values are
          between -0.615 and 0.615.
          """
          r, g, b = self.rgb
          y = 0.299 * r + 0.587 * g + 0.114 * b
          return (
                  y,
                  0.492 * (b - y),
                  0.877 * (r - y),
                  )
  
      @property
      def yuv_bytes(self):
          """
          Returns a 3-tuple of (y, u, v) byte values. Y values are biased by 16
          in the result to prevent negatives. U and V values are biased by 128
          for the same purpose.
          """
          r, g, b = self.rgb_bytes
          return (
                  (( 66 * r + 129 * g +  25 * b + 128) >> 8) + 16,
                  ((-38 * r -  73 * g + 112 * b + 128) >> 8) + 128,
                  ((112 * r -  94 * g -  18 * b + 128) >> 8) + 128,
                  )
  
      @property
      def yiq(self):
          """
          Returns a 3-tuple of (y, i, q) float values; y values can be between
          0.0 and 1.0, whilst i and q values can be between -1.0 and 1.0.
          """
          return colorsys.rgb_to_yiq(self.red, self.green, self.blue)
  
      @property
      def hls(self):
          """
          Returns a 3-tuple of (hue, lightness, saturation) float values (between
          0.0 and 1.0).
          """
          return colorsys.rgb_to_hls(self.red, self.green, self.blue)
  
      @property
      def hsv(self):
          """
          Returns a 3-tuple of (hue, saturation, value) float values (between 0.0
          and 1.0).
          """
          return colorsys.rgb_to_hsv(self.red, self.green, self.blue)
  
      @property
      def red(self):
          """
          Returns the red component of the color as a :class:`Red` instance which
          can be used in operations with other :class:`Color` instances.
          """
          # super() calls needed here to avoid recursion
          return Red(super(Color, self).red)
  
      @property
      def green(self):
          """
          Returns the green component of the color as a :class:`Green` instance
          which can be used in operations with other :class:`Color` instances.
          """
          return Green(super(Color, self).green)
  
      @property
      def blue(self):
          """
          Returns the blue component of the color as a :class:`Blue` instance
          which can be used in operations with other :class:`Color` instances.
          """
          return Blue(super(Color, self).blue)
  
      @property
      def hue(self):
          """
          Returns the hue of the color as a :class:`Hue` instance which can be
          used in operations with other :class:`Color` instances.
          """
          return Hue(self.hls[0])
  
      @property
      def lightness(self):
          """
          Returns the lightness of the color as a :class:`Lightness` instance
          which can be used in operations with other :class:`Color` instances.
          """
          return Lightness(self.hls[1])
  
      @property
      def saturation(self):
          """
          Returns the saturation of the color as a :class:`Saturation` instance
          which can be used in operations with other :class:`Color` instances.
          """
          return Saturation(self.hls[2])
  
  