colour.models.log_decoding_Log2

colour.models.log_decoding_Log2(log_norm: ArrayLike, middle_grey: float = 0.18, min_exposure: float = -6.5, max_exposure: float = 6.5) → NDArrayFloat

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

Parameters:

• log_norm (ArrayLike) – Non-linear Log2 encoded data.

• middle_grey (float) – Middle Grey exposure value.

• min_exposure (float) – Minimum exposure level.

• max_exposure (float) – Maximum exposure level.

Returns:

Linear Log2 decoded data.

Return type:

numpy.ndarray

Notes

Domain	Scale - Reference	Scale - 1
log_norm	1	1

Range	Scale - Reference	Scale - 1
lin	1	1

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

• The shaper with logarithmic encoded values can be decoded back to linear domain:

  Shaper Range	Shaper Domain
  [0, 1]	[0.002, 16.291]

References

[TheAoMPAaSciencesScienceaTCouncilAcademyCESACESPSubcommitteec]

Examples

>>> log_decoding_Log2(0.5)
0.1799999...