def test_nan_oetf_HLG_BT2100(self):
"""
Tests :func:`colour.models.rgb.transfer_functions.itur_bt_2100.\
oetf_HLG_BT2100` definition nan support.
"""
oetf_HLG_BT2100(np.array([-1.0, 0.0, 1.0, -np.inf, np.inf, np.nan]))
def test_oetf_HLG_BT2100(self):
"""
Tests :func:`colour.models.rgb.transfer_functions.itur_bt_2100.\
oetf_HLG_BT2100` definition.
"""
self.assertAlmostEqual(oetf_HLG_BT2100(0.0), 0.0, places=7)
self.assertAlmostEqual(
oetf_HLG_BT2100(0.18 / 12), 0.212132034355964, places=7)
self.assertAlmostEqual(
oetf_HLG_BT2100(1.0), 0.999999995536569, places=7)
def test_domain_range_scale_oetf_HLG_BT2100(self):
"""
Tests :func:`colour.models.rgb.transfer_functions.itur_bt_2100.\
oetf_HLG_BT2100` definition domain and range scale support.
"""
E = 0.18 / 12
E_p = oetf_HLG_BT2100(E)
d_r = (('reference', 1), (1, 1), (100, 100))
for scale, factor in d_r:
with domain_range_scale(scale):
np.testing.assert_almost_equal(
oetf_HLG_BT2100(E * factor), E_p * factor, decimal=7)
def test_n_dimensional_oetf_HLG_BT2100(self):
"""
Tests :func:`colour.models.rgb.transfer_functions.itur_bt_2100.\
oetf_HLG_BT2100` definition n-dimensional arrays support.
"""
E = 0.18 / 12
E_p = oetf_HLG_BT2100(E)
E = np.tile(E, 6)
E_p = np.tile(E_p, 6)
np.testing.assert_almost_equal(oetf_HLG_BT2100(E), E_p, decimal=7)
E = np.reshape(E, (2, 3))
E_p = np.reshape(E_p, (2, 3))
np.testing.assert_almost_equal(oetf_HLG_BT2100(E), E_p, decimal=7)
E = np.reshape(E, (2, 3, 1))
E_p = np.reshape(E_p, (2, 3, 1))
np.testing.assert_almost_equal(oetf_HLG_BT2100(E), E_p, decimal=7)
def RGB_to_ICtCp(
RGB: ArrayLike,
method: Union[Literal["Dolby 2016", "ITU-R BT.2100-1 HLG",
"ITU-R BT.2100-1 PQ", "ITU-R BT.2100-2 HLG",
"ITU-R BT.2100-2 PQ", ], str, ] = "Dolby 2016",
L_p: Floating = 10000,
) -> NDArray:
"""
Convert from *ITU-R BT.2020* colourspace to :math:`IC_TC_P` colour
encoding.
Parameters
----------
RGB
*ITU-R BT.2020* colourspace array.
method
Computation method. *Recommendation ITU-R BT.2100* defines multiple
variants of the :math:`IC_TC_P` colour encoding:
- *ITU-R BT.2100-1*
- *SMPTE ST 2084:2014* inverse electro-optical transfer
function (EOTF) and the :math:`IC_TC_P` matrix from
:cite:`Dolby2016a`: *Dolby 2016*, *ITU-R BT.2100-1 PQ*,
*ITU-R BT.2100-2 PQ* methods.
- *Recommendation ITU-R BT.2100* *Reference HLG* opto-electrical
transfer function (OETF) and the :math:`IC_TC_P` matrix
from :cite:`Dolby2016a`: *ITU-R BT.2100-1 HLG* method.
- *ITU-R BT.2100-2*
- *SMPTE ST 2084:2014* inverse electro-optical transfer
function (EOTF) and the :math:`IC_TC_P` matrix from
:cite:`Dolby2016a`: *Dolby 2016*, *ITU-R BT.2100-1 PQ*,
*ITU-R BT.2100-2 PQ* methods.
- *Recommendation ITU-R BT.2100* *Reference HLG* opto-electrical
transfer function (OETF) and a custom :math:`IC_TC_P`
matrix from :cite:`InternationalTelecommunicationUnion2018`:
*ITU-R BT.2100-2 HLG* method.
L_p
Display peak luminance :math:`cd/m^2` for *SMPTE ST 2084:2014*
non-linear encoding. This parameter should stay at its default
:math:`10000 cd/m^2` value for practical applications. It is exposed so
that the definition can be used as a fitting function.
Returns
-------
:class:`numpy.ndarray`
:math:`IC_TC_P` colour encoding array.
Warnings
--------
The underlying *SMPTE ST 2084:2014* transfer function is an absolute
transfer function.
Notes
-----
- The *ITU-R BT.2100-1 PQ* and *ITU-R BT.2100-2 PQ* methods are aliases
for the *Dolby 2016* method.
- The underlying *SMPTE ST 2084:2014* transfer function is an absolute
transfer function, thus the domain and range values for the *Reference*
and *1* scales are only indicative that the data is not affected by
scale transformations. The effective domain of *SMPTE ST 2084:2014*
inverse electro-optical transfer function (EOTF) is
[0.0001, 10000].
+------------+-----------------------+------------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+==================+
| ``RGB`` | ``UN`` | ``UN`` |
+------------+-----------------------+------------------+
+------------+-----------------------+------------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+==================+
| ``ICtCp`` | ``I`` : [0, 1] | ``I`` : [0, 1] |
| | | |
| | ``CT`` : [-1, 1] | ``CT`` : [-1, 1] |
| | | |
| | ``CP`` : [-1, 1] | ``CP`` : [-1, 1] |
+------------+-----------------------+------------------+
References
----------
:cite:`Dolby2016a`, :cite:`Lu2016c`
Examples
--------
>>> RGB = np.array([0.45620519, 0.03081071, 0.04091952])
>>> RGB_to_ICtCp(RGB) # doctest: +ELLIPSIS
array([ 0.0735136..., 0.0047525..., 0.0935159...])
>>> RGB_to_ICtCp(RGB, method='ITU-R BT.2100-2 HLG') # doctest: +ELLIPSIS
array([ 0.6256789..., -0.0198449..., 0.3591125...])
"""
RGB = as_float_array(RGB)
method = validate_method(
method,
[
"Dolby 2016",
"ITU-R BT.2100-1 HLG",
"ITU-R BT.2100-1 PQ",
"ITU-R BT.2100-2 HLG",
"ITU-R BT.2100-2 PQ",
],
)
is_hlg_method = "hlg" in method
is_BT2100_2_method = "2100-2" in method
LMS = vector_dot(MATRIX_ICTCP_RGB_TO_LMS, RGB)
with domain_range_scale("ignore"):
LMS_p = (oetf_HLG_BT2100(LMS)
if is_hlg_method else eotf_inverse_ST2084(LMS, L_p))
ICtCp = (vector_dot(MATRIX_ICTCP_LMS_P_TO_ICTCP_HLG_BT2100_2, LMS_p) if
(is_hlg_method and is_BT2100_2_method) else vector_dot(
MATRIX_ICTCP_LMS_P_TO_ICTCP, LMS_p))
return ICtCp