"""
Spectral Bandpass Dependence Correction
=======================================
Define objects to perform spectral bandpass dependence correction.
The following correction methods are available:
- :func:`colour.colorimetry.bandpass_correction_Stearns1988`:
*Stearns and Stearns (1988)* spectral bandpass dependence correction
method.
- :attr:`colour.BANDPASS_CORRECTION_METHODS`: Supported spectral bandpass
dependence correction methods.
- :func:`colour.bandpass_correction`: Spectral bandpass dependence
correction using the specified method.
References
----------
- :cite:`Stearns1988a` : Stearns, E. I., & Stearns, R. E. (1988). An example
of a method for correcting radiance data for Bandpass error. Color Research
& Application, 13(4), 257-259. doi:10.1002/col.5080130410
- :cite:`Westland2012f` : Westland, S., Ripamonti, C., & Cheung, V. (2012).
Correction for Spectral Bandpass. In Computational Colour Science Using
MATLAB (2nd ed., p. 38). ISBN:978-0-470-66569-5
"""
from __future__ import annotations
import typing
if typing.TYPE_CHECKING:
from colour.colorimetry import SpectralDistribution
from colour.hints import Literal
from colour.utilities import CanonicalMapping, validate_method
__author__ = "Colour Developers"
__copyright__ = "Copyright 2013 Colour Developers"
__license__ = "BSD-3-Clause - https://opensource.org/licenses/BSD-3-Clause"
__maintainer__ = "Colour Developers"
__email__ = "colour-developers@colour-science.org"
__status__ = "Production"
__all__ = [
"bandpass_correction_Stearns1988",
"BANDPASS_CORRECTION_METHODS",
"bandpass_correction",
]
CONSTANT_ALPHA_STEARNS: float = 0.083
[docs]
def bandpass_correction_Stearns1988(
sd: SpectralDistribution,
) -> SpectralDistribution:
"""
Apply spectral bandpass dependence correction to the specified spectral
distribution using *Stearns and Stearns (1988)* method.
Parameters
----------
sd
Spectral distribution.
Returns
-------
:class:`colour.SpectralDistribution`
Spectral bandpass dependence corrected spectral distribution.
References
----------
:cite:`Stearns1988a`, :cite:`Westland2012f`
Examples
--------
>>> from colour import SpectralDistribution
>>> from colour.utilities import numpy_print_options
>>> data = {
... 500: 0.0651,
... 520: 0.0705,
... 540: 0.0772,
... 560: 0.0870,
... 580: 0.1128,
... 600: 0.1360,
... }
>>> with numpy_print_options(suppress=True):
... bandpass_correction_Stearns1988(SpectralDistribution(data))
... # doctest: +ELLIPSIS
SpectralDistribution([[500. , 0.0646518...],
[520. , 0.0704293...],
[540. , 0.0769485...],
[560. , 0.0856928...],
[580. , 0.1129644...],
[600. , 0.1379256...]],
SpragueInterpolator,
{},
Extrapolator,
{'method': 'Constant', 'left': None, 'right': None})
"""
A_S = CONSTANT_ALPHA_STEARNS
values = sd.values
values[0] = (1 + A_S) * values[0] - A_S * values[1]
values[-1] = (1 + A_S) * values[-1] - A_S * values[-2]
for i in range(1, len(values) - 1):
values[i] = (
-A_S * values[i - 1] + (1 + 2 * A_S) * values[i] - A_S * values[i + 1]
)
sd.values = values
return sd
BANDPASS_CORRECTION_METHODS: CanonicalMapping = CanonicalMapping(
{"Stearns 1988": bandpass_correction_Stearns1988}
)
BANDPASS_CORRECTION_METHODS.__doc__ = """
Supported spectral bandpass dependence correction methods.
"""
[docs]
def bandpass_correction(
sd: SpectralDistribution,
method: Literal["Stearns 1988"] | str = "Stearns 1988",
) -> SpectralDistribution:
"""
Apply spectral bandpass dependence correction to the specified spectral
distribution.
Correct for the systematic errors introduced by finite bandpass
measurements in spectrophotometry. The correction compensates for the
deviation between the measured spectral values and the true spectral
values that would be obtained with infinitesimal bandpass width.
Parameters
----------
sd
Spectral distribution requiring bandpass correction.
method
Bandpass correction method to apply.
Returns
-------
:class:`colour.SpectralDistribution`
Spectral distribution with bandpass dependence correction applied,
preserving the original wavelength sampling.
References
----------
:cite:`Stearns1988a`, :cite:`Westland2012f`
Examples
--------
>>> from colour import SpectralDistribution
>>> from colour.utilities import numpy_print_options
>>> data = {
... 500: 0.0651,
... 520: 0.0705,
... 540: 0.0772,
... 560: 0.0870,
... 580: 0.1128,
... 600: 0.1360,
... }
>>> with numpy_print_options(suppress=True):
... bandpass_correction(SpectralDistribution(data))
... # doctest: +ELLIPSIS
SpectralDistribution([[500. , 0.0646518...],
[520. , 0.0704293...],
[540. , 0.0769485...],
[560. , 0.0856928...],
[580. , 0.1129644...],
[600. , 0.1379256...]],
SpragueInterpolator,
{},
Extrapolator,
{'method': 'Constant', 'left': None, 'right': None})
"""
method = validate_method(method, tuple(BANDPASS_CORRECTION_METHODS))
return BANDPASS_CORRECTION_METHODS[method](sd)
