colour.models.log_encoding_Log2

colour.models.log_encoding_Log2(lin: ArrayLike, middle_grey: float = 0.18, min_exposure: float = -6.5, max_exposure: float = 6.5) → NDArrayFloat

Apply the common Log2 log encoding opto-electronic transfer function (OETF).

Parameters:

• lin (ArrayLike) – Linear Log2 decoded data.

• middle_grey (float) – Middle Grey exposure value.

• min_exposure (float) – Minimum exposure level.

• max_exposure (float) – Maximum exposure level.

Returns:

Non-linear Log2 encoded data.

Return type:

numpy.ndarray

Notes

Domain	Scale - Reference	Scale - 1
lin	1	1

Range	Scale - Reference	Scale - 1
log_norm	1	1

• 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

[TheAoMPAaSciencesScienceaTCouncilAcademyCESACESPSubcommitteeb]

Examples

>>> log_encoding_Log2(0.18)
0.5