def test_sd_CIE_illuminant_D_series(self):
"""
Tests :func:`colour.colorimetry.illuminants.\
sd_CIE_illuminant_D_series` definition.
"""
for name, CCT, tolerance in (
('D50', 5000, 0.001),
('D55', 5500, 0.001),
('D65', 6500, 0.00001),
('D75', 7500, 0.0001),
):
CCT = CCT * 1.4388 / 1.4380
xy = CCT_to_xy_CIE_D(CCT)
sd_r = ILLUMINANTS_SDS[name]
sd_t = sd_CIE_illuminant_D_series(xy)
np.testing.assert_allclose(sd_r.values,
sd_t[sd_r.wavelengths],
rtol=tolerance,
atol=tolerance)
def test_sd_CIE_illuminant_D_series(self):
"""
Tests :func:`colour.colorimetry.illuminants.\
sd_CIE_illuminant_D_series` definition.
"""
for name, CCT, tolerance in (
('D50', 5000, 0.001),
('D55', 5500, 0.001),
('D65', 6500, 0.00001),
('D75', 7500, 0.0001),
):
CCT = CCT * 1.4388 / 1.4380
xy = CCT_to_xy_CIE_D(CCT)
sd_r = ILLUMINANTS_SDS[name]
sd_t = sd_CIE_illuminant_D_series(xy)
np.testing.assert_allclose(
sd_r.values,
sd_t[sd_r.wavelengths],
rtol=tolerance,
atol=tolerance)
def colour_rendering_index(sd_test, additional_data=False):
"""
Returns the *Colour Rendering Index* (CRI) :math:`Q_a` of given spectral
distribution.
Parameters
----------
sd_test : SpectralDistribution
Test spectral distribution.
additional_data : bool, optional
Whether to output additional data.
Returns
-------
numeric or CRI_Specification
*Colour Rendering Index* (CRI).
References
----------
:cite:`Ohno2008a`
Examples
--------
>>> from colour import ILLUMINANTS_SDS
>>> sd = ILLUMINANTS_SDS['FL2']
>>> colour_rendering_index(sd) # doctest: +ELLIPSIS
64.1515202...
"""
cmfs = STANDARD_OBSERVERS_CMFS['CIE 1931 2 Degree Standard Observer'].copy(
).trim(DEFAULT_SPECTRAL_SHAPE)
shape = cmfs.shape
sd_test = sd_test.copy().align(shape)
tcs_sds = {sd.name: sd.copy().align(shape) for sd in TCS_SDS.values()}
with domain_range_scale('1'):
XYZ = sd_to_XYZ(sd_test, cmfs)
uv = UCS_to_uv(XYZ_to_UCS(XYZ))
CCT, _D_uv = uv_to_CCT_Robertson1968(uv)
if CCT < 5000:
sd_reference = sd_blackbody(CCT, shape)
else:
xy = CCT_to_xy_CIE_D(CCT)
sd_reference = sd_CIE_illuminant_D_series(xy)
sd_reference.align(shape)
test_tcs_colorimetry_data = tcs_colorimetry_data(sd_test,
sd_reference,
tcs_sds,
cmfs,
chromatic_adaptation=True)
reference_tcs_colorimetry_data = tcs_colorimetry_data(
sd_reference, sd_reference, tcs_sds, cmfs)
Q_as = colour_rendering_indexes(test_tcs_colorimetry_data,
reference_tcs_colorimetry_data)
Q_a = np.average(
[v.Q_a for k, v in Q_as.items() if k in (1, 2, 3, 4, 5, 6, 7, 8)])
if additional_data:
return CRI_Specification(
sd_test.name, Q_a, Q_as,
(test_tcs_colorimetry_data, reference_tcs_colorimetry_data))
else:
return Q_a
def colour_quality_scale(sd_test,
additional_data=False,
method='NIST CQS 9.0'):
"""
Returns the *Colour Quality Scale* (CQS) of given spectral distribution
using given method.
Parameters
----------
sd_test : SpectralDistribution
Test spectral distribution.
additional_data : bool, optional
Whether to output additional data.
method : unicode, optional
**{'NIST CQS 9.0', 'NIST CQS 7.4'}**,
Computation method.
Returns
-------
numeric or CQS_Specification
Color quality scale.
References
----------
:cite:`Davis2010a`, :cite:`Ohno2008a`, :cite:`Ohno2013`
Examples
--------
>>> from colour import ILLUMINANTS_SDS
>>> sd = ILLUMINANTS_SDS['FL2']
>>> colour_quality_scale(sd) # doctest: +ELLIPSIS
64.0172835...
"""
method = method.lower()
assert method.lower() in [
m.lower() for m in COLOUR_QUALITY_SCALE_METHODS
], ('"{0}" method is invalid, must be one of {1}!'.format(
method, COLOUR_QUALITY_SCALE_METHODS))
cmfs = STANDARD_OBSERVERS_CMFS['CIE 1931 2 Degree Standard Observer'].copy(
).trim(DEFAULT_SPECTRAL_SHAPE)
shape = cmfs.shape
sd_test = sd_test.copy().align(shape)
vs_sds = {
sd.name: sd.copy().align(shape)
for sd in VS_SDS[method].values()
}
with domain_range_scale('1'):
XYZ = sd_to_XYZ(sd_test, cmfs)
uv = UCS_to_uv(XYZ_to_UCS(XYZ))
CCT, _D_uv = uv_to_CCT_Ohno2013(uv)
if CCT < 5000:
sd_reference = sd_blackbody(CCT, shape)
else:
xy = CCT_to_xy_CIE_D(CCT)
sd_reference = sd_CIE_illuminant_D_series(xy)
sd_reference.align(shape)
test_vs_colorimetry_data = vs_colorimetry_data(sd_test,
sd_reference,
vs_sds,
cmfs,
chromatic_adaptation=True)
reference_vs_colorimetry_data = vs_colorimetry_data(
sd_reference, sd_reference, vs_sds, cmfs)
if method == 'nist cqs 9.0':
CCT_f = 1
scaling_f = 3.2
else:
XYZ_r = sd_to_XYZ(sd_reference, cmfs)
XYZ_r /= XYZ_r[1]
CCT_f = CCT_factor(reference_vs_colorimetry_data, XYZ_r)
scaling_f = 3.104
Q_as = colour_quality_scales(test_vs_colorimetry_data,
reference_vs_colorimetry_data, scaling_f,
CCT_f)
D_E_RMS = delta_E_RMS(Q_as, 'D_E_ab')
D_Ep_RMS = delta_E_RMS(Q_as, 'D_Ep_ab')
Q_a = scale_conversion(D_Ep_RMS, CCT_f, scaling_f)
if method == 'nist cqs 9.0':
scaling_f = 2.93 * 1.0343
else:
scaling_f = 2.928
Q_f = scale_conversion(D_E_RMS, CCT_f, scaling_f)
G_t = gamut_area(
[vs_CQS_data.Lab for vs_CQS_data in test_vs_colorimetry_data])
G_r = gamut_area(
[vs_CQS_data.Lab for vs_CQS_data in reference_vs_colorimetry_data])
Q_g = G_t / D65_GAMUT_AREA * 100
if method == 'nist cqs 9.0':
Q_d = Q_p = None
else:
p_delta_C = np.average([
sample_data.D_C_ab if sample_data.D_C_ab > 0 else 0
for sample_data in Q_as.values()
])
Q_p = 100 - 3.6 * (D_Ep_RMS - p_delta_C)
Q_d = G_t / G_r * CCT_f * 100
if additional_data:
return CQS_Specification(
sd_test.name, Q_a, Q_f, Q_p, Q_g, Q_d, Q_as,
(test_vs_colorimetry_data, reference_vs_colorimetry_data))
else:
return Q_a
def colour_quality_scale(sd_test, additional_data=False,
method='NIST CQS 9.0'):
"""
Returns the *Colour Quality Scale* (CQS) of given spectral distribution
using given method.
Parameters
----------
sd_test : SpectralDistribution
Test spectral distribution.
additional_data : bool, optional
Whether to output additional data.
method : unicode, optional
**{'NIST CQS 9.0', 'NIST CQS 7.4'}**,
Computation method.
Returns
-------
numeric or CQS_Specification
Color quality scale.
References
----------
:cite:`Davis2010a`, :cite:`Ohno2008a`, :cite:`Ohno2013`
Examples
--------
>>> from colour import ILLUMINANTS_SDS
>>> sd = ILLUMINANTS_SDS['FL2']
>>> colour_quality_scale(sd) # doctest: +ELLIPSIS
64.0172835...
"""
method = method.lower()
assert method.lower() in [
m.lower() for m in COLOUR_QUALITY_SCALE_METHODS
], ('"{0}" method is invalid, must be one of {1}!'.format(
method, COLOUR_QUALITY_SCALE_METHODS))
cmfs = STANDARD_OBSERVERS_CMFS['CIE 1931 2 Degree Standard Observer'].copy(
).trim(ASTME30815_PRACTISE_SHAPE)
shape = cmfs.shape
sd_test = sd_test.copy().align(shape)
vs_sds = {
sd.name: sd.copy().align(shape)
for sd in VS_SDS[method].values()
}
with domain_range_scale('1'):
XYZ = sd_to_XYZ(sd_test, cmfs)
uv = UCS_to_uv(XYZ_to_UCS(XYZ))
CCT, _D_uv = uv_to_CCT_Ohno2013(uv)
if CCT < 5000:
sd_reference = sd_blackbody(CCT, shape)
else:
xy = CCT_to_xy_CIE_D(CCT)
sd_reference = sd_CIE_illuminant_D_series(xy)
sd_reference.align(shape)
test_vs_colorimetry_data = vs_colorimetry_data(
sd_test, sd_reference, vs_sds, cmfs, chromatic_adaptation=True)
reference_vs_colorimetry_data = vs_colorimetry_data(
sd_reference, sd_reference, vs_sds, cmfs)
if method == 'nist cqs 9.0':
CCT_f = 1
scaling_f = 3.2
else:
XYZ_r = sd_to_XYZ(sd_reference, cmfs)
XYZ_r /= XYZ_r[1]
CCT_f = CCT_factor(reference_vs_colorimetry_data, XYZ_r)
scaling_f = 3.104
Q_as = colour_quality_scales(test_vs_colorimetry_data,
reference_vs_colorimetry_data, scaling_f,
CCT_f)
D_E_RMS = delta_E_RMS(Q_as, 'D_E_ab')
D_Ep_RMS = delta_E_RMS(Q_as, 'D_Ep_ab')
Q_a = scale_conversion(D_Ep_RMS, CCT_f, scaling_f)
if method == 'nist cqs 9.0':
scaling_f = 2.93 * 1.0343
else:
scaling_f = 2.928
Q_f = scale_conversion(D_E_RMS, CCT_f, scaling_f)
G_t = gamut_area(
[vs_CQS_data.Lab for vs_CQS_data in test_vs_colorimetry_data])
G_r = gamut_area(
[vs_CQS_data.Lab for vs_CQS_data in reference_vs_colorimetry_data])
Q_g = G_t / D65_GAMUT_AREA * 100
if method == 'nist cqs 9.0':
Q_d = Q_p = None
else:
p_delta_C = np.average([
sample_data.D_C_ab if sample_data.D_C_ab > 0 else 0
for sample_data in Q_as.values()
])
Q_p = 100 - 3.6 * (D_Ep_RMS - p_delta_C)
Q_d = G_t / G_r * CCT_f * 100
if additional_data:
return CQS_Specification(
sd_test.name, Q_a, Q_f, Q_p, Q_g, Q_d, Q_as,
(test_vs_colorimetry_data, reference_vs_colorimetry_data))
else:
return Q_a
def sd_reference_illuminant(CCT: Floating,
shape: SpectralShape) -> SpectralDistribution:
"""
Compute the reference illuminant for a given correlated colour temperature
:math:`T_{cp}` for use in *CIE 2017 Colour Fidelity Index* (CFI)
computation.
Parameters
----------
CCT
Correlated colour temperature :math:`T_{cp}`.
shape
Desired shape of the returned spectral distribution.
Returns
-------
:class:`colour.SpectralDistribution`
Reference illuminant for *CIE 2017 Colour Fidelity Index* (CFI)
computation.
Examples
--------
>>> from colour.utilities import numpy_print_options
>>> with numpy_print_options(suppress=True):
... sd_reference_illuminant( # doctest: +ELLIPSIS
... 4224.469705295263300, SpectralShape(380, 780, 20))
SpectralDistribution([[ 380. , 0.0034089...],
[ 400. , 0.0044208...],
[ 420. , 0.0053260...],
[ 440. , 0.0062857...],
[ 460. , 0.0072767...],
[ 480. , 0.0080207...],
[ 500. , 0.0086590...],
[ 520. , 0.0092242...],
[ 540. , 0.0097686...],
[ 560. , 0.0101444...],
[ 580. , 0.0104475...],
[ 600. , 0.0107642...],
[ 620. , 0.0110439...],
[ 640. , 0.0112535...],
[ 660. , 0.0113922...],
[ 680. , 0.0115185...],
[ 700. , 0.0113155...],
[ 720. , 0.0108192...],
[ 740. , 0.0111582...],
[ 760. , 0.0101299...],
[ 780. , 0.0105638...]],
interpolator=SpragueInterpolator,
interpolator_kwargs={},
extrapolator=Extrapolator,
extrapolator_kwargs={...})
"""
if CCT <= 5000:
sd_planckian = sd_blackbody(CCT, shape)
if CCT >= 4000:
xy = CCT_to_xy_CIE_D(CCT)
sd_daylight = sd_CIE_illuminant_D_series(xy).align(shape)
if CCT < 4000:
sd_reference = sd_planckian
elif 4000 <= CCT <= 5000:
# Planckian and daylight illuminant must be normalised so that the
# mixture isn't biased.
sd_planckian /= sd_to_XYZ(sd_planckian)[1] # type: ignore[misc]
sd_daylight /= sd_to_XYZ(sd_daylight)[1] # type: ignore[misc]
# Mixture: 4200K should be 80% Planckian, 20% CIE Illuminant D Series.
m = (CCT - 4000) / 1000
values = linstep_function(m, sd_planckian.values, sd_daylight.values)
name = (f"{as_int_scalar(CCT)}K "
f"Blackbody & CIE Illuminant D Series Mixture - "
f"{as_float_scalar(100 * m):.1f}%")
sd_reference = SpectralDistribution(values, shape.range(), name=name)
elif CCT > 5000:
sd_reference = sd_daylight
return sd_reference
def colour_rendering_index(sd_test, additional_data=False):
"""
Returns the *Colour Rendering Index* (CRI) :math:`Q_a` of given spectral
distribution.
Parameters
----------
sd_test : SpectralDistribution
Test spectral distribution.
additional_data : bool, optional
Whether to output additional data.
Returns
-------
numeric or CRI_Specification
*Colour Rendering Index* (CRI).
References
----------
:cite:`Ohno2008a`
Examples
--------
>>> from colour import ILLUMINANTS_SDS
>>> sd = ILLUMINANTS_SDS['FL2']
>>> colour_rendering_index(sd) # doctest: +ELLIPSIS
64.1515202...
"""
cmfs = STANDARD_OBSERVERS_CMFS['CIE 1931 2 Degree Standard Observer'].copy(
).trim(ASTME30815_PRACTISE_SHAPE)
shape = cmfs.shape
sd_test = sd_test.copy().align(shape)
tcs_sds = {sd.name: sd.copy().align(shape) for sd in TCS_SDS.values()}
with domain_range_scale('1'):
XYZ = sd_to_XYZ(sd_test, cmfs)
uv = UCS_to_uv(XYZ_to_UCS(XYZ))
CCT, _D_uv = uv_to_CCT_Robertson1968(uv)
if CCT < 5000:
sd_reference = sd_blackbody(CCT, shape)
else:
xy = CCT_to_xy_CIE_D(CCT)
sd_reference = sd_CIE_illuminant_D_series(xy)
sd_reference.align(shape)
test_tcs_colorimetry_data = tcs_colorimetry_data(
sd_test, sd_reference, tcs_sds, cmfs, chromatic_adaptation=True)
reference_tcs_colorimetry_data = tcs_colorimetry_data(
sd_reference, sd_reference, tcs_sds, cmfs)
Q_as = colour_rendering_indexes(test_tcs_colorimetry_data,
reference_tcs_colorimetry_data)
Q_a = np.average(
[v.Q_a for k, v in Q_as.items() if k in (1, 2, 3, 4, 5, 6, 7, 8)])
if additional_data:
return CRI_Specification(
sd_test.name, Q_a, Q_as,
(test_tcs_colorimetry_data, reference_tcs_colorimetry_data))
else:
return Q_a
def colour_quality_scale(sd_test, additional_data=False):
"""
Returns the *Colour Quality Scale* (CQS) of given spectral
distribution.
Parameters
----------
sd_test : SpectralDistribution
Test spectral distribution.
additional_data : bool, optional
Whether to output additional data.
Returns
-------
numeric or CQS_Specification
Color quality scale.
References
----------
:cite:`Davis2010a`, :cite:`Ohno2008a`
Examples
--------
>>> from colour import ILLUMINANTS_SDS
>>> sd = ILLUMINANTS_SDS['FL2']
>>> colour_quality_scale(sd) # doctest: +ELLIPSIS
64.6863391...
"""
cmfs = STANDARD_OBSERVERS_CMFS['CIE 1931 2 Degree Standard Observer'].copy(
).trim(ASTME30815_PRACTISE_SHAPE)
shape = cmfs.shape
sd_test = sd_test.copy().align(shape)
vs_sds = {sd.name: sd.copy().align(shape) for sd in VS_SDS.values()}
with domain_range_scale('1'):
XYZ = sd_to_XYZ(sd_test, cmfs)
uv = UCS_to_uv(XYZ_to_UCS(XYZ))
CCT, _D_uv = uv_to_CCT_Ohno2013(uv)
if CCT < 5000:
sd_reference = sd_blackbody(CCT, shape)
else:
xy = CCT_to_xy_CIE_D(CCT)
sd_reference = sd_CIE_illuminant_D_series(xy)
sd_reference.align(shape)
test_vs_colorimetry_data = vs_colorimetry_data(sd_test,
sd_reference,
vs_sds,
cmfs,
chromatic_adaptation=True)
reference_vs_colorimetry_data = vs_colorimetry_data(
sd_reference, sd_reference, vs_sds, cmfs)
XYZ_r = sd_to_XYZ(sd_reference, cmfs)
XYZ_r /= XYZ_r[1]
CCT_f = CCT_factor(reference_vs_colorimetry_data, XYZ_r)
Q_as = colour_quality_scales(test_vs_colorimetry_data,
reference_vs_colorimetry_data, CCT_f)
D_E_RMS = delta_E_RMS(Q_as, 'D_E_ab')
D_Ep_RMS = delta_E_RMS(Q_as, 'D_Ep_ab')
Q_a = scale_conversion(D_Ep_RMS, CCT_f)
Q_f = scale_conversion(D_E_RMS, CCT_f, 2.928)
p_delta_C = np.average(
[sample_data.D_C_ab if sample_data.D_C_ab > 0 else 0
for sample_data in Q_as.values()]) # yapf: disable
Q_p = 100 - 3.6 * (D_Ep_RMS - p_delta_C)
G_t = gamut_area(
[vs_CQS_data.Lab for vs_CQS_data in test_vs_colorimetry_data])
G_r = gamut_area(
[vs_CQS_data.Lab for vs_CQS_data in reference_vs_colorimetry_data])
Q_g = G_t / D65_GAMUT_AREA * 100
Q_d = G_t / G_r * CCT_f * 100
if additional_data:
return CQS_Specification(
sd_test.name, Q_a, Q_f, Q_p, Q_g, Q_d, Q_as,
(test_vs_colorimetry_data, reference_vs_colorimetry_data))
else:
return Q_a
def generate_illuminants_rawtoaces_v1() -> CaseInsensitiveMapping:
"""
Generate a series of illuminants according to *RAW to ACES* v1:
- *CIE Illuminant D Series* in range [4000, 25000] kelvin degrees.
- *Blackbodies* in range [1000, 3500] kelvin degrees.
- A.M.P.A.S. variant of *ISO 7589 Studio Tungsten*.
Returns
-------
:class:`colour.utilities.CaseInsensitiveMapping`
Series of illuminants.
Notes
-----
- This definition introduces a few differences compared to
*RAW to ACES* v1: *CIE Illuminant D Series* are computed in range
[4002.15, 7003.77] kelvin degrees and the :math:`C_2` change is not
used in *RAW to ACES* v1.
References
----------
:cite:`Dyer2017`
Examples
--------
>>> list(sorted(generate_illuminants_rawtoaces_v1().keys()))
['1000K Blackbody', '1500K Blackbody', '2000K Blackbody', \
'2500K Blackbody', '3000K Blackbody', '3500K Blackbody', 'D100', 'D105', \
'D110', 'D115', 'D120', 'D125', 'D130', 'D135', 'D140', 'D145', 'D150', \
'D155', 'D160', 'D165', 'D170', 'D175', 'D180', 'D185', 'D190', 'D195', \
'D200', 'D205', 'D210', 'D215', 'D220', 'D225', 'D230', 'D235', 'D240', \
'D245', 'D250', 'D40', 'D45', 'D50', 'D55', 'D60', 'D65', 'D70', 'D75', \
'D80', 'D85', 'D90', 'D95', 'iso7589']
"""
global _ILLUMINANTS_RAWTOACES_V1
if _ILLUMINANTS_RAWTOACES_V1 is not None:
illuminants = _ILLUMINANTS_RAWTOACES_V1
else:
illuminants = CaseInsensitiveMapping()
# CIE Illuminants D Series from 4000K to 25000K.
for i in np.arange(4000, 25000 + 500, 500):
CCT = i * 1.4388 / 1.4380
xy = CCT_to_xy_CIE_D(CCT)
sd = sd_CIE_illuminant_D_series(xy)
sd.name = f"D{int(CCT / 100):d}"
illuminants[sd.name] = sd.align(SPECTRAL_SHAPE_RAWTOACES)
# TODO: Remove when removing the "colour.sd_blackbody" definition
# warning.
with suppress_warnings(colour_usage_warnings=True):
# Blackbody from 1000K to 4000K.
for i in np.arange(1000, 4000, 500):
sd = sd_blackbody(i, SPECTRAL_SHAPE_RAWTOACES)
illuminants[sd.name] = sd
# A.M.P.A.S. variant of ISO 7589 Studio Tungsten.
sd = read_sds_from_csv_file(
os.path.join(RESOURCES_DIRECTORY_RAWTOACES,
"AMPAS_ISO_7589_Tungsten.csv"))["iso7589"]
illuminants.update({sd.name: sd})
_ILLUMINANTS_RAWTOACES_V1 = illuminants
return illuminants
def colour_rendering_index(
sd_test: SpectralDistribution, additional_data: Boolean = False
) -> Union[Floating, ColourRendering_Specification_CRI]:
"""
Return the *Colour Rendering Index* (CRI) :math:`Q_a` of given spectral
distribution.
Parameters
----------
sd_test
Test spectral distribution.
additional_data
Whether to output additional data.
Returns
-------
:class:`numpy.floating` or \
:class:`colour.quality.ColourRendering_Specification_CRI`
*Colour Rendering Index* (CRI).
References
----------
:cite:`Ohno2008a`
Examples
--------
>>> from colour import SDS_ILLUMINANTS
>>> sd = SDS_ILLUMINANTS['FL2']
>>> colour_rendering_index(sd) # doctest: +ELLIPSIS
64.2337241...
"""
# pylint: disable=E1102
cmfs = reshape_msds(
MSDS_CMFS["CIE 1931 2 Degree Standard Observer"],
SPECTRAL_SHAPE_DEFAULT,
)
shape = cmfs.shape
sd_test = reshape_sd(sd_test, shape)
tcs_sds = {sd.name: reshape_sd(sd, shape) for sd in SDS_TCS.values()}
with domain_range_scale("1"):
XYZ = sd_to_XYZ(sd_test, cmfs)
uv = UCS_to_uv(XYZ_to_UCS(XYZ))
CCT, _D_uv = uv_to_CCT_Robertson1968(uv)
if CCT < 5000:
sd_reference = sd_blackbody(CCT, shape)
else:
xy = CCT_to_xy_CIE_D(CCT)
sd_reference = sd_CIE_illuminant_D_series(xy)
sd_reference.align(shape)
test_tcs_colorimetry_data = tcs_colorimetry_data(
sd_test, sd_reference, tcs_sds, cmfs, chromatic_adaptation=True
)
reference_tcs_colorimetry_data = tcs_colorimetry_data(
sd_reference, sd_reference, tcs_sds, cmfs
)
Q_as = colour_rendering_indexes(
test_tcs_colorimetry_data, reference_tcs_colorimetry_data
)
Q_a = as_float_scalar(
np.average(
[v.Q_a for k, v in Q_as.items() if k in (1, 2, 3, 4, 5, 6, 7, 8)]
)
)
if additional_data:
return ColourRendering_Specification_CRI(
sd_test.name,
Q_a,
Q_as,
(test_tcs_colorimetry_data, reference_tcs_colorimetry_data),
)
else:
return Q_a
def colour_quality_scale(
sd_test: SpectralDistribution,
additional_data: Boolean = False,
method: Union[Literal["NIST CQS 7.4", "NIST CQS 9.0"],
str] = "NIST CQS 9.0",
) -> Union[Floating, ColourRendering_Specification_CQS]:
"""
Return the *Colour Quality Scale* (CQS) of given spectral distribution
using given method.
Parameters
----------
sd_test
Test spectral distribution.
additional_data
Whether to output additional data.
method
Computation method.
Returns
-------
:class:`numpy.floating` or \
:class:`colour.quality.ColourRendering_Specification_CQS`
*Colour Quality Scale* (CQS).
References
----------
:cite:`Davis2010a`, :cite:`Ohno2008a`, :cite:`Ohno2013`
Examples
--------
>>> from colour import SDS_ILLUMINANTS
>>> sd = SDS_ILLUMINANTS['FL2']
>>> colour_quality_scale(sd) # doctest: +ELLIPSIS
64.1117031...
"""
method = validate_method(method, COLOUR_QUALITY_SCALE_METHODS)
# pylint: disable=E1102
cmfs = reshape_msds(
MSDS_CMFS["CIE 1931 2 Degree Standard Observer"],
SPECTRAL_SHAPE_DEFAULT,
)
shape = cmfs.shape
sd_test = reshape_sd(sd_test, shape)
vs_sds = {sd.name: reshape_sd(sd, shape) for sd in SDS_VS[method].values()}
with domain_range_scale("1"):
XYZ = sd_to_XYZ(sd_test, cmfs)
uv = UCS_to_uv(XYZ_to_UCS(XYZ))
CCT, _D_uv = uv_to_CCT_Ohno2013(uv)
if CCT < 5000:
sd_reference = sd_blackbody(CCT, shape)
else:
xy = CCT_to_xy_CIE_D(CCT)
sd_reference = sd_CIE_illuminant_D_series(xy)
sd_reference.align(shape)
test_vs_colorimetry_data = vs_colorimetry_data(sd_test,
sd_reference,
vs_sds,
cmfs,
chromatic_adaptation=True)
reference_vs_colorimetry_data = vs_colorimetry_data(
sd_reference, sd_reference, vs_sds, cmfs)
CCT_f: Floating
if method == "nist cqs 9.0":
CCT_f = 1
scaling_f = 3.2
else:
XYZ_r = sd_to_XYZ(sd_reference, cmfs)
XYZ_r /= XYZ_r[1]
CCT_f = CCT_factor(reference_vs_colorimetry_data, XYZ_r)
scaling_f = 3.104
Q_as = colour_quality_scales(
test_vs_colorimetry_data,
reference_vs_colorimetry_data,
scaling_f,
CCT_f,
)
D_E_RMS = delta_E_RMS(Q_as, "D_E_ab")
D_Ep_RMS = delta_E_RMS(Q_as, "D_Ep_ab")
Q_a = scale_conversion(D_Ep_RMS, CCT_f, scaling_f)
if method == "nist cqs 9.0":
scaling_f = 2.93 * 1.0343
else:
scaling_f = 2.928
Q_f = scale_conversion(D_E_RMS, CCT_f, scaling_f)
G_t = gamut_area(
[vs_CQS_data.Lab for vs_CQS_data in test_vs_colorimetry_data])
G_r = gamut_area(
[vs_CQS_data.Lab for vs_CQS_data in reference_vs_colorimetry_data])
Q_g = G_t / GAMUT_AREA_D65 * 100
if method == "nist cqs 9.0":
Q_p = Q_d = None
else:
p_delta_C = np.average([
sample_data.D_C_ab if sample_data.D_C_ab > 0 else 0
for sample_data in Q_as.values()
])
Q_p = as_float_scalar(100 - 3.6 * (D_Ep_RMS - p_delta_C))
Q_d = as_float_scalar(G_t / G_r * CCT_f * 100)
if additional_data:
return ColourRendering_Specification_CQS(
sd_test.name,
Q_a,
Q_f,
Q_p,
Q_g,
Q_d,
Q_as,
(test_vs_colorimetry_data, reference_vs_colorimetry_data),
)
else:
return Q_a
