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https://github.com/vaab/colour

Python color representations manipulation library (RGB, HSL, web, ...)
https://github.com/vaab/colour

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Python color representations manipulation library (RGB, HSL, web, ...)

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README 

        
======

Colour

======



.. image:: http://img.shields.io/pypi/v/colour.svg?style=flat

   :target: https://pypi.python.org/pypi/colour/

   :alt: Latest PyPI version



.. image:: https://img.shields.io/pypi/l/gitchangelog.svg?style=flat

   :target: https://github.com/vaab/gitchangelog/blob/master/LICENSE

   :alt: License



.. image:: https://img.shields.io/pypi/pyversions/gitchangelog.svg?style=flat

   :target: https://pypi.python.org/pypi/gitchangelog/

   :alt: Compatible python versions



.. image:: http://img.shields.io/pypi/dm/colour.svg?style=flat

   :target: https://pypi.python.org/pypi/colour/

   :alt: Number of PyPI downloads



.. image:: http://img.shields.io/travis/vaab/colour/master.svg?style=flat

   :target: https://travis-ci.org/vaab/colour/

   :alt: Travis CI build status



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   :target: https://ci.appveyor.com/project/vaab/colour/branch/master

   :alt: Appveyor CI build status



.. image:: http://img.shields.io/codecov/c/github/vaab/colour.svg?style=flat

   :target: https://codecov.io/gh/vaab/colour/

   :alt: Test coverage



Converts and manipulates common color representation (RGB, HSL, web, ...)



Feature

=======



- Damn simple and pythonic way to manipulate color representation (see

  examples below)



- Full conversion between RGB, HSL, 6-digit hex, 3-digit hex, human color



- One object (``Color``) or bunch of single purpose function (``rgb2hex``,

  ``hsl2rgb`` ...)



- ``web`` format that use the smallest representation between

  6-digit (e.g. ``#fa3b2c``), 3-digit (e.g. ``#fbb``), fully spelled

  color (e.g. ``white``), following `W3C color naming`_ for compatible

  CSS or HTML color specifications.



- smooth intuitive color scale generation choosing N color gradients.



- can pick colors for you to identify objects of your application.



.. _W3C color naming: http://www.w3.org/TR/css3-color/#svg-color



Installation

============



You don't need to download the GIT version of the code as ``colour`` is

available on the PyPI. So you should be able to run::



    pip install colour



If you have downloaded the GIT sources, then you could add the ``colour.py``

directly to one of your ``site-packages`` (thanks to a symlink). Or install

the current version via traditional::



    python setup.py install



And if you don't have the GIT sources but would like to get the latest

master or branch from github, you could also::



    pip install git+https://github.com/vaab/colour



Or even select a specific revision (branch/tag/commit)::



    pip install git+https://github.com/vaab/colour@master



Usage

=====



To get complete demo of each function, please read the source code which is

heavily documented and provide a lot of examples in doctest format.



Here is a reduced sample of a common usage scenario:



Instantiation

-------------



Let's create blue color::



    >>> from colour import Color

    >>> c = Color("blue")

    >>> c

    



Please note that all of these are equivalent examples to create the red color::



    Color("red")           ## human, web compatible representation

    Color(red=1)           ## default amount of blue and green is 0.0

    Color("blue", hue=0)   ## hue of blue is 0.66, hue of red is 0.0

    Color("#f00")          ## standard 3 hex digit web compatible representation

    Color("#ff0000")       ## standard 6 hex digit web compatible representation

    Color(hue=0, saturation=1, luminance=0.5)

    Color(hsl=(0, 1, 0.5)) ## full 3-uple HSL specification

    Color(rgb=(1, 0, 0))   ## full 3-uple RGB specification

    Color(Color("red"))    ## recursion doesn't break object



Reading values

--------------



Several representations are accessible::



    >>> c.hex

    '#00f'

    >>> c.hsl  # doctest: +ELLIPSIS

    (0.66..., 1.0, 0.5)

    >>> c.rgb

    (0.0, 0.0, 1.0)



And their different parts are also independently accessible, as the different

amount of red, blue, green, in the RGB format::



    >>> c.red

    0.0

    >>> c.blue

    1.0

    >>> c.green

    0.0



Or the hue, saturation and luminance of the HSL representation::



    >>> c.hue  # doctest: +ELLIPSIS

    0.66...

    >>> c.saturation

    1.0

    >>> c.luminance

    0.5



A note on the ``.hex`` property, it'll return the smallest valid value

when possible. If you are only interested by the long value, use

``.hex_l``::



    >>> c.hex_l

    '#0000ff'



Modifying color objects

-----------------------



All of these properties are read/write, so let's add some red to this color::



    >>> c.red = 1

    >>> c

    



We might want to de-saturate this color::



    >>> c.saturation = 0.5

    >>> c

    



And of course, the string conversion will give the web representation which is

human, or 3-digit, or 6-digit hex representation depending which is usable::



    >>> "%s" % c

    '#bf40bf'



    >>> c.luminance = 1

    >>> "%s" % c

    'white'



Ranges of colors

----------------



You can get some color scale of variation between two ``Color`` objects quite

easily. Here, is the color scale of the rainbow between red and blue::



    >>> red = Color("red")

    >>> blue = Color("blue")

    >>> list(red.range_to(blue, 5))

    [, , , , ]



Or the different amount of gray between black and white::



    >>> black = Color("black")

    >>> white = Color("white")

    >>> list(black.range_to(white, 6))

    [, , , , , ]



If you have to create graphical representation with color scale

between red and green ('lime' color is full green)::



    >>> lime = Color("lime")

    >>> list(red.range_to(lime, 5))

    [, , , , ]



Notice how naturally, the yellow is displayed in human format and in

the middle of the scale. And that the quite unusual (but compatible)

'chartreuse' color specification has been used in place of the

hexadecimal representation.



Color comparison

----------------



Sane default

~~~~~~~~~~~~



Color comparison is a vast subject. However, it might seem quite straightforward for

you. ``Colour`` uses a configurable default way of comparing color that might suit

your needs::



    >>> Color("red") == Color("#f00") == Color("blue", hue=0)

    True



The default comparison algorithm focuses only on the "web" representation which is

equivalent to comparing the long hex representation (e.g. #FF0000) or to be more

specific, it is equivalent to compare the amount of red, green, and blue composition

of the RGB representation, each of these value being quantized to a 256 value scale.



This default comparison is a practical and convenient way to measure the actual

color equivalence on your screen, or in your video card memory.



But this comparison wouldn't make the difference between a black red, and a

black blue, which both are black::



   >>> black_red = Color("red", luminance=0)

   >>> black_blue = Color("blue", luminance=0)



   >>> black_red == black_blue

   True



Customization

~~~~~~~~~~~~~



But, this is not the sole way to compare two colors. As I'm quite lazy, I'm providing

you a way to customize it to your needs. Thus::



   >>> from colour import RGB_equivalence, HSL_equivalence

   >>> black_red = Color("red", luminance=0, equality=HSL_equivalence)

   >>> black_blue = Color("blue", luminance=0, equality=HSL_equivalence)



   >>> black_red == black_blue

   False



As you might have already guessed, the sane default is ``RGB_equivalence``, so::



   >>> black_red = Color("red", luminance=0, equality=RGB_equivalence)

   >>> black_blue = Color("blue", luminance=0, equality=RGB_equivalence)



   >>> black_red == black_blue

   True



Here's how you could implement your unique comparison function::



   >>> saturation_equivalence = lambda c1, c2: c1.saturation == c2.saturation

   >>> red = Color("red", equality=saturation_equivalence)

   >>> blue = Color("blue", equality=saturation_equivalence)

   >>> white = Color("white", equality=saturation_equivalence)



   >>> red == blue

   True

   >>> white == red

   False



Note: When comparing 2 colors, *only* the equality function *of the first

color will be used*. Thus::



   >>> black_red = Color("red", luminance=0, equality=RGB_equivalence)

   >>> black_blue = Color("blue", luminance=0, equality=HSL_equivalence)



   >>> black_red == black_blue

   True



But reverse operation is not equivalent !::



   >>> black_blue == black_red

   False



Equality to non-Colour objects

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



As a side note, whatever your custom equality function is, it won't be

used if you compare to anything else than a ``Colour`` instance::



    >>> red = Color("red", equality=lambda c1, c2: True)

    >>> blue = Color("blue", equality=lambda c1, c2: True)



Note that these instances would compare as equal to any other color::



    >>> red == blue

    True



But on another non-Colour object::



    >>> red == None

    False

    >>> red != None

    True



Actually, ``Colour`` instances will, politely enough, leave

the other side of the equality have a chance to decide of the output,

(by executing its own ``__eq__``), so::



    >>> class OtherColorImplem(object):

    ...     def __init__(self, color):

    ...         self.color = color

    ...     def __eq__(self, other):

    ...         return self.color == other.web



    >>> alien_red = OtherColorImplem("red")

    >>> red == alien_red

    True

    >>> blue == alien_red

    False



And inequality (using ``__ne__``) are also polite::



    >>> class AnotherColorImplem(OtherColorImplem):

    ...     def __ne__(self, other):

    ...         return self.color != other.web



    >>> new_alien_red = AnotherColorImplem("red")

    >>> red != new_alien_red

    False

    >>> blue != new_alien_red

    True



Picking arbitrary color for a python object

-------------------------------------------



Basic Usage

~~~~~~~~~~~



Sometimes, you just want to pick a color for an object in your application

often to visually identify this object. Thus, the picked color should be the

same for same objects, and different for different object::



    >>> foo = object()

    >>> bar = object()



    >>> Color(pick_for=foo)  # doctest: +ELLIPSIS

    

    >>> Color(pick_for=foo) == Color(pick_for=foo)

    True

    >>> Color(pick_for=foo) == Color(pick_for=bar)

    False



Of course, although there's a tiny probability that different strings yield the

same color, most of the time, different inputs will produce different colors.



Advanced Usage

~~~~~~~~~~~~~~



You can customize your color picking algorithm by providing a ``picker``. A

``picker`` is a callable that takes an object, and returns something that can

be instantiated as a color by ``Color``::



    >>> my_picker = lambda obj: "red" if isinstance(obj, int) else "blue"

    >>> Color(pick_for=3, picker=my_picker, pick_key=None)

    

    >>> Color(pick_for="foo", picker=my_picker, pick_key=None)

    



You might want to use a particular picker, but enforce how the picker will

identify two object as the same (or not). So there's a ``pick_key`` attribute

that is provided and defaults as equivalent of ``hash`` method and if hash is

not supported by your object, it'll default to the ``str`` of your object salted

with the class name.



Thus::



    >>> class MyObj(str): pass

    >>> my_obj_color = Color(pick_for=MyObj("foo"))

    >>> my_str_color = Color(pick_for="foo")

    >>> my_obj_color == my_str_color

    False



Please make sure your object is hashable or "stringable" before using the

``RGB_color_picker`` picking mechanism or provide another color picker. Nearly

all python object are hashable by default so this shouldn't be an issue (e.g. 

instances of ``object`` and subclasses are hashable).



Neither ``hash`` nor ``str`` are perfect solution. So feel free to use

``pick_key`` at ``Color`` instantiation time to set your way to identify

objects, for instance::



    >>> a = object()

    >>> b = object()

    >>> Color(pick_for=a, pick_key=id) == Color(pick_for=b, pick_key=id)

    False



When choosing a pick key, you should closely consider if you want your color

to be consistent between runs (this is NOT the case with the last example),

or consistent with the content of your object if it is a mutable object.



Default value of ``pick_key`` and ``picker`` ensures that the same color will

be attributed to same object between different run on different computer for

most python object.



Color factory

-------------



As you might have noticed, there are few attributes that you might want to see

attached to all of your colors as ``equality`` for equality comparison support,

or ``picker``, ``pick_key`` to configure your object color picker.



You can create a customized ``Color`` factory thanks to the ``make_color_factory``::



    >>> from colour import make_color_factory, HSL_equivalence, RGB_color_picker



    >>> get_color = make_color_factory(

    ...    equality=HSL_equivalence,

    ...    picker=RGB_color_picker,

    ...    pick_key=str,

    ... )



All color created thanks to ``CustomColor`` class instead of the default one

would get the specified attributes by default::



    >>> black_red = get_color("red", luminance=0)

    >>> black_blue = get_color("blue", luminance=0)



Of course, these are always instances of ``Color`` class::



    >>> isinstance(black_red, Color)

    True



Equality was changed from normal defaults, so::



    >>> black_red == black_blue

    False



This because the default equivalence of ``Color`` was set to

``HSL_equivalence``.



Contributing

============



Any suggestion or issue is welcome. Push request are very welcome,

please check out the guidelines.



Push Request Guidelines

-----------------------



You can send any code. I'll look at it and will integrate it myself in

the code base and leave you as the author. This process can take time and

it'll take less time if you follow the following guidelines:



- check your code with PEP8 or pylint. Try to stick to 80 columns wide.

- separate your commits per smallest concern.

- each commit should pass the tests (to allow easy bisect)

- each functionality/bugfix commit should contain the code, tests,

  and doc.

- prior minor commit with typographic or code cosmetic changes are

  very welcome. These should be tagged in their commit summary with

  ``!minor``.

- the commit message should follow gitchangelog rules (check the git

  log to get examples)

- if the commit fixes an issue or finished the implementation of a

  feature, please mention it in the summary.



If you have some questions about guidelines which is not answered here,

please check the current ``git log``, you might find previous commit that

would show you how to deal with your issue.



License

=======



Copyright (c) 2012-2017 Valentin Lab.



Licensed under the `BSD License`_.



.. _BSD License: http://raw.github.com/vaab/colour/master/LICENSE