colour.models.log_encoding_Log2

colour.models.log_encoding_Log2(lin, middle_grey=0.18, min_exposure=- 6.5, max_exposure=6.5)[source]

Defines the common Log2 encoding function.

Parameters
  • lin (numeric or array_like) – Linear data to undergo encoding.

  • middle_grey (numeric, optional) – Middle Grey exposure value.

  • min_exposure (numeric, optional) – Minimum exposure level.

  • max_exposure (numeric, optional) – Maximum exposure level.

Returns

Non-linear Log2 encoded data.

Return type

numeric or ndarray

Notes

  • The common Log2 encoding function can be used to build linear to logarithmic shapers in the ACES OCIO configuration.

  • A (48-nits OCIO) shaper having values in a linear domain, can be encoded to a logarithmic domain:

    Shaper Domain

    Shaper Range

    [0.002, 16.291]

    [0, 1]

References

[TheAoMPAaSciencesScienceaTCouncilAcademyCESACESPSubcommitteea]

Examples

>>> log_encoding_Log2(0.18)
0.5