ColorCorrection Usage

Once installed with pip, importing cdl_convert works like importing any other python module.

>>> import cdl_convert as cdl

Creating ColorCorrection

Once imported, you have two choices. You can either instantiate a new, blank cdl directly, or you can parse a file on disk.

A ColorCorrection is created with the 10 required values (RGB values for slope, offset and power, and a single value for saturation) set to their defaults.

>>> cc.slope
(Decimal('1.0'), Decimal('1.0'), Decimal('1.0'))
>>> cc.offset
(Decimal('0.0'), Decimal('0.0'), Decimal('0.0'))
>>> cc.power
(Decimal('1.0'), Decimal('1.0'), Decimal('1.0'))
>>> cc.sat
Decimal('1.0')

Note

slope, offset, power and sat are convenience properties that actually reference two child objects of ColorCorrection , a SopNode and a SatNode . Calling them via cc.power is the same as calling cc.sop_node.power.

The ColorCorrection class inherits from both the AscColorSpaceBase class, and the AscDescBase class, giving it the additional attributes of input_desc (to describe the colorspace entering the correction, viewing_desc (to describe the colorspace conversions that must occur for viewing, and what type of monitor was used), and desc (which can be an infinitely long list of shot descriptions)

Direct Creation

If you want to create a new instance of ColorCorrection, you have to provide an id, for the unique cdl identifier and an optional source filename to input_file.

>>> cc = cdl.ColorCorrection(id='cc1', input_file='./myfirstcdl.cc')

Warning

When an instance of ColorCorrection is first created, the id provided is checked against a class level dictionary variable named members to ensure that no two ColorCorrection share the same id , as this is required by the specification.

Giving duplicate id will result in a number being appended to the back, unless HALT_ON_ERROR is set, in which case it will fail.

Reset the members list by calling the reset_members method of ColorCorrection or reset all class member list and dictionaries with cdl_convert.reset_all.

Parsing a single correction CDL file

Instead of creating a blank CDL object, you can parse a cc file from disk, and it will return a single ColorCorrection matching the correction found in the file. Formats that contain multiple corrections will return a ColorCollection , which contains child ColorCorrection .

If you don’t want to worry about matching the filetype to a parser, just use the generic parse_file function.

>>> cdl.parse_file('./myfirstcdl.cc')
<cdl_convert.correction.ColorCorrection object at 0x1004a5590>
>>> collection = cdl.parse_file('/myfirstedl.ccc')
<cdl_convert.collection.ColorCollection object at 0x100633b40>,
>>> collection.color_corrections
[
    <cdl_convert.correction.ColorCorrection object at 0x100633b90>,
    <cdl_convert.correction.ColorCorrection object at 0x100633c50>,
    <cdl_convert.correction.ColorCorrection object at 0x100633cd0>,
    <cdl_convert.correction.ColorCorrection object at 0x100633b50>,
    <cdl_convert.correction.ColorCorrection object at 0x100633d90>,
    <cdl_convert.correction.ColorCorrection object at 0x100633b10>,
    <cdl_convert.correction.ColorCorrection object at 0x100633ad0>,
]

Once you have a ColorCorrection from a parser, you’ll find that whatever values it found on the file now exist on the instance of ColorCorrection.

>>> cc = cdl.parse_cc('./xf/015.cc')
>>> cc.slope
(Decimal('1.02401'), Decimal('1.00804'), Decimal('0.89562'))
>>> cc.offset
(Decimal('-0.00864'), Decimal('-0.00261'), Decimal('0.03612'))
>>> cc.power
(Decimal('1.0'), Decimal('1.0'), Decimal('1.0'))
>>> cc.sat
Decimal('1.2')
>>> cc.id
'015_xf_seqGrade_v01'
>>> cc.file_in
'/Users/niven/cdls/xf/015.cc'

Note

When parsing, the id attribute is set in a variety of ways depending on how much information is available. Some formats, like cc, have an explicitly tagged id field that is always used. Other formats, like flex, have no such field and the parser tries to grab any scene/take metadata it can find to construct one. The last fallback is always the filename. For formats that can contain multiple ColorCorrection , the id has a created instance number after it.

Using ColorCorrection

Slope, Offset and Power

Setting the CDL slope, offset and power (SOP) values is as easy as passing them any list or tuple with three values. Integers, strings and floats will be automatically converted to Decimals, while slope and power will also truncate at zero.

>>> cc.slope = ('1.234', 5, 273891.37823)
>>> cc.slope
(Decimal('1.234'), Decimal('5.0'), Decimal('273891.37823'))
>>> cc.offset = (-0.0013, 0.097, 0.001)
>>> cc.offset
(Decimal('-0.0013'), Decimal('0.097'), Decimal('0.001'))
>>> cc.power = (-0.01, 1.0, 1.0)
>>> cc.power
(Decimal('0.0'), Decimal('1.0'), Decimal('1.0'))
>>> cc.power = (1.01, 1.007)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "cdl_convert/correction.py", line 306, in power
    self.sop_node.power = power_rgb
  File "cdl_convert/correction.py", line 668, in power
    value = self._check_setter_value(value, 'power')
  File "cdl_convert/correction.py", line 767, in _check_setter_value
    value = self._check_rgb_values(value, name, negative_allow)
  File "cdl_convert/correction.py", line 709, in _check_rgb_values
    values=values
ValueError: Error setting power with value: "(1.01, 1.007)". Power values given as a list or tuple must have 3 elements, one for each color.

It’s also possible to set the SOP values with a single value, and have it copy itself across all three colors. Setting SOP values this way mimics how color corrections typically start out.

>>> cc.slope = 1.2
>>> cc.slope
(Decimal('1.2'), Decimal('1.2'), Decimal('1.2'))

Saturation

Saturation is a positive float values, and the same checks and conversions that we do on SOP values happen for saturation as well.

>>> cc.sat = 1.1
>>> cc.sat
Decimal('1.1')
>>> cc.sat = '1.2'
>>> cc.sat
Decimal('1.2')
>>> cc.sat = 1
>>> cc.sat
Decimal('1.0')
>>> cc.sat = -0.1
>>> cc.sat
Decimal('0.0')

Warning

If it’s desired to have negative values raise an exception instead of truncating to zero, set the global config module variable HALT_ON_ERROR to be True.

>>> cdl.config.HALT_ON_ERROR = True
>>> cc.power = (-0.01, 1.0, 1.0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "cdl_convert/correction.py", line 306, in power
    self.sop_node.power = power_rgb
  File "cdl_convert/correction.py", line 668, in power
    value = self._check_setter_value(value, 'power')
  File "cdl_convert/correction.py", line 767, in _check_setter_value
    value = self._check_rgb_values(value, name, negative_allow)
  File "cdl_convert/correction.py", line 720, in _check_rgb_values
    negative_allow
  File "cdl_convert/base.py", line 419, in _check_single_value
    value=value
ValueError: Error setting power with value: "-0.01". Values must not be negative

Description

Certain formats of the cdl will contain multiple description entries. Each description entry is added to the desc attribute, which returns a list of the entries.

>>> cc.desc
['John enters the room', '5.6 ISO 800', 'bad take']

You can append to list by setting the description field like normal.

>>> cc.desc = 'final cc'
>>> cc.desc
['John enters the room', '5.6 ISO 800', 'bad take', 'final cc]

Setting the value to a new list or tuple will replace the list.

>>> cc.desc
['John enters the room', '5.6 ISO 800', 'bad take', 'final cc]
>>> cc.desc = ['first comment', 'second comment']
>>> cc.desc
['first comment', 'second comment']

Id and Files

When creating a ColorCorrection, the id field is checked against a global list of ColorCorrection ids, and creation fails if the id is not unique.

You can change the id after creation, but it will perform the same check.

>>> cc = cdl.ColorCorrection(id='cc1', input_file='./myfirstcdl.cc')
>>> cc2 = cdl.ColorCorrection(id='cc2', input_file='./mysecondcdl.cc')
>>> cc.id
'cc1'
>>> cc2.id
'cc2'
>>> cc2.id = 'cc1'
Traceback (most recent call last):
  File "<ipython-input-8-b2b5487dbc63>", line 1, in <module>
    cc2.id = 'cc1'
  File "cdl_convert/correction.py", line 362, in id
    self._set_id(value)
  File "cdl_convert/correction.py", line 430, in _set_id
    cc_id=cc_id
ValueError: Error setting the id to "cc1". This id is already a registered id.

A ValueError is only raised if HALT_ON_ERROR is set. If HALT_ON_ERROR is not set (default), a number will be appended to the non-duplicate ID.

So if you already have a ColorCorrection with the id of ‘sh100cc’, the second ColorCorrection you set to have that id will actually set to ‘sh100cc001’.

At the current time, file_out cannot be set directly. file_out is determined by using the class method determine_dest, which takes a provided directory, the id and figures out the output path.

>>> cc.file_in
'/Users/sean/cdls/xf/015.cc'
>>> cc.file_out
>>> cc.determine_dest('cdl', '/Users/potter/cdls/converted/')
>>> cc.id
'015_xf_seqGrade_v01'
>>> cc.file_out
'/Users/potter/cdls/converted/015_xf_seqGrade_v01.cdl'

Writing ColorCorrection

When you’re done tinkering with the ColorCorrection instance, you might want to write it out to a file. We need to give ColorCorrection the file extension we plan to write to, then call a write function with our ColorCorrection instance, which will actually convert the values on the ColorCorrection into the format desired, then write that format to disk.

>>> cc.determine_dest('cdl', '/Users/potter/cdls/converted/')
>>> cc.file_out
'/Users/potter/cdls/converted/015_xf_seqGrade_v01.cdl'
>>> cdl.write_cdl(cc)

Warning

It is highly likely that in the future, these will be methods on the ColorCorrection class itself, and that instead of writing the file directly, they will instead return a string formatted for writing.