def XYZ_to_sRGB(XYZ,
illuminant=RGB_COLOURSPACES['sRGB'].whitepoint,
chromatic_adaptation_transform='CAT02',
apply_encoding_cctf=True):
"""
Converts from *CIE XYZ* tristimulus values to *sRGB* colourspace.
Parameters
----------
XYZ : array_like
*CIE XYZ* tristimulus values.
illuminant : array_like, optional
Source illuminant chromaticity coordinates.
chromatic_adaptation_transform : unicode, optional
**{'CAT02', 'XYZ Scaling', 'Von Kries', 'Bradford', 'Sharp',
'Fairchild', 'CMCCAT97', 'CMCCAT2000', 'CAT02_BRILL_CAT', 'Bianco',
'Bianco PC'}**,
*Chromatic adaptation* transform.
apply_encoding_cctf : bool, optional
Apply *sRGB* encoding colour component transfer function /
opto-electronic transfer function.
Returns
-------
ndarray
*sRGB* colour array.
Notes
-----
- Input *CIE XYZ* tristimulus values are in domain [0, 1].
Examples
--------
>>> import numpy as np
>>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313])
>>> XYZ_to_sRGB(XYZ) # doctest: +ELLIPSIS
array([ 0.1749881..., 0.3881947..., 0.3216031...])
"""
sRGB = RGB_COLOURSPACES['sRGB']
return XYZ_to_RGB(
XYZ,
illuminant,
sRGB.whitepoint,
sRGB.XYZ_to_RGB_matrix,
chromatic_adaptation_transform,
sRGB.encoding_cctf if apply_encoding_cctf else None) # yapf: disable
def XYZ_to_sRGB(
XYZ,
illuminant=ILLUMINANTS['CIE 1931 2 Degree Standard Observer']['D65'],
chromatic_adaptation_transform='CAT02',
apply_encoding_cctf=True):
"""
Converts from *CIE XYZ* tristimulus values to *sRGB* colourspace.
Parameters
----------
XYZ : array_like
*CIE XYZ* tristimulus values.
illuminant : array_like, optional
Source illuminant chromaticity coordinates.
chromatic_adaptation_transform : unicode, optional
**{'CAT02', 'XYZ Scaling', 'Von Kries', 'Bradford', 'Sharp',
'Fairchild', 'CMCCAT97', 'CMCCAT2000', 'CAT02_BRILL_CAT', 'Bianco',
'Bianco PC'}**,
*Chromatic adaptation* transform.
apply_encoding_cctf : bool, optional
Apply *sRGB* encoding colour component transfer function /
opto-electronic transfer function.
Returns
-------
ndarray
*sRGB* colour array.
Notes
-----
+------------+-----------------------+---------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``XYZ`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``RGB`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
Examples
--------
>>> import numpy as np
>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
>>> XYZ_to_sRGB(XYZ) # doctest: +ELLIPSIS
array([ 0.7057393..., 0.1924826..., 0.2235416...])
"""
sRGB = RGB_COLOURSPACES['sRGB']
return XYZ_to_RGB(
XYZ,
illuminant,
sRGB.whitepoint,
sRGB.XYZ_to_RGB_matrix,
chromatic_adaptation_transform,
sRGB.encoding_cctf if apply_encoding_cctf else None,
)
def sd_to_aces_relative_exposure_values(
sd,
illuminant=ILLUMINANTS_SDS['D65'],
apply_chromatic_adaptation=False,
chromatic_adaptation_transform='CAT02'):
"""
Converts given spectral distribution to *ACES2065-1* colourspace relative
exposure values.
Parameters
----------
sd : SpectralDistribution
Spectral distribution.
illuminant : SpectralDistribution, optional
*Illuminant* spectral distribution.
apply_chromatic_adaptation : bool, optional
Whether to apply chromatic adaptation using given transform.
chromatic_adaptation_transform : unicode, optional
**{'CAT02', 'XYZ Scaling', 'Von Kries', 'Bradford', 'Sharp',
'Fairchild', 'CMCCAT97', 'CMCCAT2000', 'CAT02_BRILL_CAT', 'Bianco',
'Bianco PC'}**,
*Chromatic adaptation* transform.
Returns
-------
ndarray, (3,)
*ACES2065-1* colourspace relative exposure values array.
Notes
-----
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``XYZ`` | [0, 100] | [0, 1] |
+------------+-----------------------+---------------+
- The chromatic adaptation method implemented here is a bit unusual
as it involves building a new colourspace based on *ACES2065-1*
colourspace primaries but using the whitepoint of the illuminant that
the spectral distribution was measured under.
References
----------
:cite:`Forsythe2018`,
:cite:`TheAcademyofMotionPictureArtsandSciences2014q`,
:cite:`TheAcademyofMotionPictureArtsandSciences2014r`,
:cite:`TheAcademyofMotionPictureArtsandSciencese`
Examples
--------
>>> from colour import COLOURCHECKERS_SDS
>>> sd = COLOURCHECKERS_SDS['ColorChecker N Ohta']['dark skin']
>>> sd_to_aces_relative_exposure_values(sd) # doctest: +ELLIPSIS
array([ 0.1171785..., 0.0866347..., 0.0589707...])
>>> sd_to_aces_relative_exposure_values(sd,
... apply_chromatic_adaptation=True) # doctest: +ELLIPSIS
array([ 0.1180766..., 0.0869023..., 0.0589104...])
"""
shape = ACES_RICD.shape
if sd.shape != ACES_RICD.shape:
sd = sd.copy().align(shape)
if illuminant.shape != ACES_RICD.shape:
illuminant = illuminant.copy().align(shape)
s_v = sd.values
i_v = illuminant.values
r_bar, g_bar, b_bar = tsplit(ACES_RICD.values)
def k(x, y):
"""
Computes the :math:`K_r`, :math:`K_g` or :math:`K_b` scale factors.
"""
return 1 / np.sum(x * y)
k_r = k(i_v, r_bar)
k_g = k(i_v, g_bar)
k_b = k(i_v, b_bar)
E_r = k_r * np.sum(i_v * s_v * r_bar)
E_g = k_g * np.sum(i_v * s_v * g_bar)
E_b = k_b * np.sum(i_v * s_v * b_bar)
E_rgb = np.array([E_r, E_g, E_b])
# Accounting for flare.
E_rgb += FLARE_PERCENTAGE
E_rgb *= S_FLARE_FACTOR
if apply_chromatic_adaptation:
xy = XYZ_to_xy(sd_to_XYZ(illuminant) / 100)
NPM = normalised_primary_matrix(ACES_2065_1_COLOURSPACE.primaries, xy)
XYZ = RGB_to_XYZ(E_rgb, xy, ACES_2065_1_COLOURSPACE.whitepoint, NPM,
chromatic_adaptation_transform)
E_rgb = XYZ_to_RGB(XYZ, ACES_2065_1_COLOURSPACE.whitepoint,
ACES_2065_1_COLOURSPACE.whitepoint,
ACES_2065_1_COLOURSPACE.XYZ_to_RGB_matrix)
return from_range_1(E_rgb)
def XYZ_to_sRGB(
XYZ,
illuminant=CCS_ILLUMINANTS['CIE 1931 2 Degree Standard Observer']
['D65'],
chromatic_adaptation_transform='CAT02',
apply_cctf_encoding=True,
**kwargs):
"""
Converts from *CIE XYZ* tristimulus values to *sRGB* colourspace.
Parameters
----------
XYZ : array_like
*CIE XYZ* tristimulus values.
illuminant : array_like, optional
Source illuminant chromaticity coordinates.
chromatic_adaptation_transform : unicode, optional
**{'CAT02', 'XYZ Scaling', 'Von Kries', 'Bradford', 'Sharp',
'Fairchild', 'CMCCAT97', 'CMCCAT2000', 'CAT02 Brill 2008',
'Bianco 2010', 'Bianco PC 2010'}**,
*Chromatic adaptation* transform.
apply_cctf_encoding : bool, optional
Apply *sRGB* encoding colour component transfer function /
opto-electronic transfer function.
Other Parameters
----------------
\\**kwargs : dict, optional
Keywords arguments for deprecation management.
Returns
-------
ndarray
*sRGB* colour array.
Notes
-----
+------------+-----------------------+---------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``XYZ`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``RGB`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
Examples
--------
>>> import numpy as np
>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
>>> XYZ_to_sRGB(XYZ) # doctest: +ELLIPSIS
array([ 0.7057393..., 0.1924826..., 0.2235416...])
"""
apply_cctf_encoding = handle_arguments_deprecation(
{
'ArgumentRenamed': [['apply_encoding_cctf', 'apply_cctf_encoding']
],
}, **kwargs).get('apply_cctf_encoding', apply_cctf_encoding)
sRGB = RGB_COLOURSPACES['sRGB']
return XYZ_to_RGB(
XYZ,
illuminant,
sRGB.whitepoint,
sRGB.matrix_XYZ_to_RGB,
chromatic_adaptation_transform,
sRGB.cctf_encoding if apply_cctf_encoding else None,
)
def XYZ_to_ICtCp(
XYZ: ArrayLike,
illuminant=CCS_ILLUMINANTS["CIE 1931 2 Degree Standard Observer"]["D65"],
chromatic_adaptation_transform: Union[Literal["Bianco 2010",
"Bianco PC 2010", "Bradford",
"CAT02 Brill 2008", "CAT02",
"CAT16", "CMCCAT2000",
"CMCCAT97", "Fairchild",
"Sharp", "Von Kries",
"XYZ Scaling", ],
str, ] = "CAT02",
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 *CIE XYZ* tristimulus values to :math:`IC_TC_P` colour
encoding.
Parameters
----------
XYZ
*CIE XYZ* tristimulus values.
illuminant
Source illuminant chromaticity coordinates.
chromatic_adaptation_transform
*Chromatic adaptation* transform.
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 underlying *SMPTE ST 2084:2014* transfer function is an absolute
transfer function, thus the domain and range values for the *Reference*
- The *ITU-R BT.2100-1 PQ* and *ITU-R BT.2100-2 PQ* methods are aliases
for the *Dolby 2016* method.
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** |
+============+=======================+==================+
| ``XYZ`` | ``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
--------
>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
>>> XYZ_to_ICtCp(XYZ) # doctest: +ELLIPSIS
array([ 0.0685809..., -0.0028384..., 0.0602098...])
>>> XYZ_to_ICtCp(XYZ, method='ITU-R BT.2100-2 HLG') # doctest: +ELLIPSIS
array([ 0.5924279..., -0.0374073..., 0.2512267...])
"""
BT2020 = RGB_COLOURSPACES["ITU-R BT.2020"]
RGB = XYZ_to_RGB(
XYZ,
illuminant,
BT2020.whitepoint,
BT2020.matrix_XYZ_to_RGB,
chromatic_adaptation_transform,
)
return RGB_to_ICtCp(RGB, method, L_p)
def XYZ_to_sRGB(
XYZ: ArrayLike,
illuminant: ArrayLike = CCS_ILLUMINANTS[
"CIE 1931 2 Degree Standard Observer"]["D65"],
chromatic_adaptation_transform: Union[Literal["Bianco 2010",
"Bianco PC 2010", "Bradford",
"CAT02 Brill 2008", "CAT02",
"CAT16", "CMCCAT2000",
"CMCCAT97", "Fairchild",
"Sharp", "Von Kries",
"XYZ Scaling", ],
str, ] = "CAT02",
apply_cctf_encoding: Boolean = True,
) -> NDArray:
"""
Convert from *CIE XYZ* tristimulus values to *sRGB* colourspace.
Parameters
----------
XYZ
*CIE XYZ* tristimulus values.
illuminant
Source illuminant chromaticity coordinates.
chromatic_adaptation_transform
*Chromatic adaptation* transform.
apply_cctf_encoding
Whether to apply the *sRGB* encoding colour component transfer function
/ inverse electro-optical transfer function.
Returns
-------
:class:`numpy.ndarray`
*sRGB* colour array.
Notes
-----
+------------+-----------------------+---------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``XYZ`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``RGB`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
Examples
--------
>>> import numpy as np
>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
>>> XYZ_to_sRGB(XYZ) # doctest: +ELLIPSIS
array([ 0.7057393..., 0.1924826..., 0.2235416...])
"""
sRGB = RGB_COLOURSPACES["sRGB"]
return XYZ_to_RGB(
XYZ,
illuminant,
sRGB.whitepoint,
sRGB.matrix_XYZ_to_RGB,
chromatic_adaptation_transform,
sRGB.cctf_encoding if apply_cctf_encoding else None,
)
def sd_to_aces_relative_exposure_values(
sd: SpectralDistribution,
illuminant: Optional[SpectralDistribution] = None,
apply_chromatic_adaptation: Boolean = False,
chromatic_adaptation_transform: Union[Literal["Bianco 2010",
"Bianco PC 2010", "Bradford",
"CAT02 Brill 2008", "CAT02",
"CAT16", "CMCCAT2000",
"CMCCAT97", "Fairchild",
"Sharp", "Von Kries",
"XYZ Scaling", ],
str, ] = "CAT02",
) -> NDArray:
"""
Convert given spectral distribution to *ACES2065-1* colourspace relative
exposure values.
Parameters
----------
sd
Spectral distribution.
illuminant
*Illuminant* spectral distribution, default to
*CIE Standard Illuminant D65*.
apply_chromatic_adaptation
Whether to apply chromatic adaptation using given transform.
chromatic_adaptation_transform
*Chromatic adaptation* transform.
Returns
-------
:class:`numpy.ndarray`
*ACES2065-1* colourspace relative exposure values array.
Notes
-----
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``XYZ`` | [0, 100] | [0, 1] |
+------------+-----------------------+---------------+
- The chromatic adaptation method implemented here is a bit unusual
as it involves building a new colourspace based on *ACES2065-1*
colourspace primaries but using the whitepoint of the illuminant that
the spectral distribution was measured under.
References
----------
:cite:`Forsythe2018`,
:cite:`TheAcademyofMotionPictureArtsandSciences2014q`,
:cite:`TheAcademyofMotionPictureArtsandSciences2014r`,
:cite:`TheAcademyofMotionPictureArtsandSciencese`
Examples
--------
>>> from colour import SDS_COLOURCHECKERS
>>> sd = SDS_COLOURCHECKERS['ColorChecker N Ohta']['dark skin']
>>> sd_to_aces_relative_exposure_values(sd) # doctest: +ELLIPSIS
array([ 0.1171814..., 0.0866360..., 0.0589726...])
>>> sd_to_aces_relative_exposure_values(sd,
... apply_chromatic_adaptation=True) # doctest: +ELLIPSIS
array([ 0.1180779..., 0.0869031..., 0.0589125...])
"""
illuminant = cast(SpectralDistribution,
optional(illuminant, SDS_ILLUMINANTS["D65"]))
shape = MSDS_ACES_RICD.shape
if sd.shape != MSDS_ACES_RICD.shape:
sd = reshape_sd(sd, shape)
if illuminant.shape != MSDS_ACES_RICD.shape:
illuminant = reshape_sd(illuminant, shape)
s_v = sd.values
i_v = illuminant.values
r_bar, g_bar, b_bar = tsplit(MSDS_ACES_RICD.values)
def k(x: NDArray, y: NDArray) -> NDArray:
"""Compute the :math:`K_r`, :math:`K_g` or :math:`K_b` scale factors."""
return 1 / np.sum(x * y)
k_r = k(i_v, r_bar)
k_g = k(i_v, g_bar)
k_b = k(i_v, b_bar)
E_r = k_r * np.sum(i_v * s_v * r_bar)
E_g = k_g * np.sum(i_v * s_v * g_bar)
E_b = k_b * np.sum(i_v * s_v * b_bar)
E_rgb = np.array([E_r, E_g, E_b])
# Accounting for flare.
E_rgb += FLARE_PERCENTAGE
E_rgb *= S_FLARE_FACTOR
if apply_chromatic_adaptation:
xy = XYZ_to_xy(sd_to_XYZ(illuminant) / 100)
NPM = normalised_primary_matrix(RGB_COLOURSPACE_ACES2065_1.primaries,
xy)
XYZ = RGB_to_XYZ(
E_rgb,
xy,
RGB_COLOURSPACE_ACES2065_1.whitepoint,
NPM,
chromatic_adaptation_transform,
)
E_rgb = XYZ_to_RGB(
XYZ,
RGB_COLOURSPACE_ACES2065_1.whitepoint,
RGB_COLOURSPACE_ACES2065_1.whitepoint,
RGB_COLOURSPACE_ACES2065_1.matrix_XYZ_to_RGB,
)
return from_range_1(E_rgb)
