colour.models.rgb.transfer_functions.gamma Module¶
Gamma Colour Component Transfer Function¶
Defines gamma encoding / decoding colour component transfer function related objects:
See also
-
colour.models.rgb.transfer_functions.gamma.
gamma_function
(a, exponent=1, negative_number_handling=u'indeterminate')[source]¶ Defines a typical gamma encoding / decoding function.
Parameters: - a (numeric or array_like) – Array to encode / decode.
- exponent (numeric or array_like, optional) – Encoding / decoding exponent.
- negative_number_handling (unicode, optional) –
{‘Indeterminate’, ‘Mirror’, ‘Preserve’, ‘Clamp’}, Defines the behaviour for a negative numbers and / or the definition return value:
- Indeterminate: The behaviour will be indeterminate and definition return value might contain nans.
- Mirror: The definition return value will be mirrored around abscissa and ordinate axis, i.e. Blackmagic Design: Davinci Resolve behaviour.
- Preserve: The definition will preserve any negative number in a, i.e. The Foundry Nuke behaviour.
- Clamp: The definition will clamp any negative number in a to 0.
Returns: Encoded / decoded array.
Return type: numeric or ndarray
Raises: ValueError
– If the negative number handling method is not defined.Examples
>>> gamma_function(0.18, 2.2) 0.0229932... >>> gamma_function(-0.18, 2.0) 0.0323999... >>> gamma_function(-0.18, 2.2) nan >>> gamma_function(-0.18, 2.2, 'Mirror') -0.0229932... >>> gamma_function(-0.18, 2.2, 'Preserve') -0.1... >>> gamma_function(-0.18, 2.2, 'Clamp') 0.0