Colorimetry

Spectral Data Structure

colour

MultiSpectralDistributions([data, domain, ...])	Define multi-spectral distributions: the base object for multi-spectral computations.
SpectralDistribution([data, domain])	Define the spectral distribution: the base object for spectral computations.
SpectralShape(start, end, interval)	Define the base object for spectral distribution shape.

SPECTRAL_SHAPE_ASTME308	Define the spectral shape for ASTM E308-15 practice with wavelength range from 360 to 780 nm at 1 nm intervals: (360, 780, 1).
SPECTRAL_SHAPE_DEFAULT	Define the spectral shape for ASTM E308-15 practice with wavelength range from 360 to 780 nm at 1 nm intervals: (360, 780, 1).

Ancillary Objects

colour.colorimetry

reshape_msds(msds[, shape, method, copy])	Reshape the specified multi-spectral distributions to match the specified spectral shape.
reshape_sd(sd[, shape, method, copy])	Reshape the specified spectral distribution to match the specified spectral shape.
sds_and_msds_to_msds(sds)	Convert specified spectral and multi-spectral distributions to multi-spectral distributions.
sds_and_msds_to_sds(sds)	Convert specified spectral and multi-spectral distributions to a list of spectral distributions.

Spectral Data Generation

colour

msds_constant(k, labels[, shape])	Generate multi-spectral distributions with the specified labels and spectral shape filled with constant \(k\) values.
msds_ones(labels[, shape])	Generate multi-spectral distributions with the specified labels and spectral shape filled with ones.
msds_zeros(labels[, shape])	Generate multi-spectral distributions with the specified labels and spectral shape filled with zeros.
sd_blackbody(temperature[, shape, c1, c2, n])	Generate the spectral distribution of the planckian radiator for the specified temperature \(T[K]\) with values in watts per steradian per square metre per nanometre (\(W/sr/m^2/nm\)).
sd_CIE_illuminant_D_series(xy[, ...])	Return the spectral distribution of the specified CIE Illuminant D Series using the specified CIE xy chromaticity coordinates.
sd_CIE_standard_illuminant_A([shape])	Represent typical domestic tungsten-filament lighting according to CIE Standard Illuminant A.
sd_constant(k[, shape])	Generate a spectral distribution of the specified spectral shape filled with constant \(k\) values.
sd_gaussian(mu_peak_wavelength, sigma_fwhm)	Generate a Gaussian spectral distribution with the specified spectral shape using the specified method.
SD_GAUSSIAN_METHODS	Supported gaussian spectral distribution generation methods.
sd_multi_leds(peak_wavelengths[, shape, method])	Generate a multi-LED spectral distribution with the specified spectral shape at specified peak wavelengths.
SD_MULTI_LEDS_METHODS	Supported multi-LED spectral distribution computation methods.
sd_ones([shape])	Generate a spectral distribution of the specified spectral shape filled with ones.
sd_rayleigh_jeans(temperature[, shape])	Generate the spectral distribution of the planckian radiator for the specified temperature \(T[K]\) with values in watts per steradian per square metre per nanometre (\(W/sr/m^2/nm\)) according to the Rayleigh-Jeans law.
sd_single_led(peak_wavelength[, shape, method])	Generate a single LED spectral distribution with the specified spectral shape at the specified peak wavelength using the specified method.
SD_SINGLE_LED_METHODS	Supported single LED spectral distribution computation methods.
sd_zeros([shape])	Generate a spectral distribution of the specified spectral shape filled with zeros.

colour.colorimetry

blackbody_spectral_radiance(wavelength, ...)	Compute the spectral radiance of a blackbody as a function of wavelength at specified thermodynamic temperature \(T[K]\) in a medium with index of refraction \(n\).
daylight_locus_function(x_D)	Compute the CIE y chromaticity coordinate on the daylight locus.
planck_law(wavelength, temperature[, c1, c2, n])	Compute the spectral radiance of a blackbody as a function of wavelength at specified thermodynamic temperature \(T[K]\) in a medium with index of refraction \(n\).
rayleigh_jeans_law(wavelength, temperature)	Approximate the spectral radiance of a blackbody as a function of wavelength at specified thermodynamic temperature \(T[K]\) according to the Rayleigh-Jeans law.
sd_gaussian_fwhm(peak_wavelength, fwhm[, shape])	Generate a Gaussian spectral distribution of the specified spectral shape at specified peak wavelength and full width at half maximum (FWHM).
sd_gaussian_normal(mu, sigma[, shape])	Generate a Gaussian spectral distribution of the specified spectral shape at specified mean wavelength \(\mu\) and standard deviation \(\sigma\).
sd_gaussian_super_clamped(peak_wavelength, fwhm)	Generate a super-Gaussian spectral distribution, optionally clamped flat on one side of the peak, with the peak normalized to 1.
sd_multi_leds_Ohno2005(peak_wavelengths, ...)	Generate a multi-LED spectral distribution with the specified spectral shape at specified peak wavelengths, half spectral widths \(\Delta\lambda_{0.5}\), and peak power ratios according to the Ohno (2005) method.
sd_single_led_Ohno2005(peak_wavelength, ...)	Generate a single LED spectral distribution with the specified spectral shape at specified peak wavelength and half spectral width \(\Delta\lambda_{0.5}\) using Ohno (2005) method.

Aliases

colour.colorimetry

planck_law(wavelength, temperature[, c1, c2, n])

Compute the spectral radiance of a blackbody as a function of wavelength at specified thermodynamic temperature \(T[K]\) in a medium with index of refraction \(n\).

Conversion to Tristimulus Values

colour

msds_to_XYZ(msds[, cmfs, illuminant, k, method])	Convert specified multi-spectral distributions to CIE XYZ tristimulus values using the specified colour matching functions and illuminant.
MSDS_TO_XYZ_METHODS	Supported multi-spectral distributions to CIE XYZ tristimulus values conversion methods.
sd_to_XYZ(sd[, cmfs, illuminant, k, method])	Convert specified spectral distribution to CIE XYZ tristimulus values using specified colour matching functions, illuminant and method.
SD_TO_XYZ_METHODS	Supported spectral distribution to CIE XYZ tristimulus values conversion methods.
wavelength_to_XYZ(wavelength[, cmfs])	Convert the specified wavelength \(\lambda\) to CIE XYZ tristimulus values using the specified colour matching functions.

Ancillary Objects

colour.colorimetry

handle_spectral_arguments([cmfs, ...])

Handle spectral arguments for various Colour definitions that perform spectral computations.

ASTM E308-15

colour.colorimetry

msds_to_XYZ_ASTME308(msds[, cmfs, ...])	Convert specified multi-spectral distributions to CIE XYZ tristimulus values using the specified colour matching functions and illuminant according to practise ASTM E308-15 method.
sd_to_XYZ_ASTME308(sd[, cmfs, illuminant, ...])	Convert the specified spectral distribution to CIE XYZ tristimulus values using the specified colour matching functions and illuminant according to practice ASTM E308-15 method.

Ancillary Objects

colour.colorimetry

adjust_tristimulus_weighting_factors_ASTME308(W, ...)	Adjust the specified table of tristimulus weighting factors to account for a shorter wavelength range of the test spectral shape compared to the reference spectral shape using practice ASTM E308-15 method.
lagrange_coefficients_ASTME2022([interval, ...])	Compute Lagrange Coefficients for the specified interval size using practice ASTM E2022-11 method.
sd_to_XYZ_tristimulus_weighting_factors_ASTME308(sd)	Convert the specified spectral distribution to CIE XYZ tristimulus values using the specified colour matching functions and illuminant with a table of tristimulus weighting factors according to the ASTM E308-15 method.
tristimulus_weighting_factors_ASTME2022(...)	Compute a table of tristimulus weighting factors for the specified colour matching functions and illuminant using practise ASTM E2022-11 method.

Integration

colour.colorimetry

msds_to_XYZ_integration(msds[, cmfs, ...])	Convert the specified multi-spectral distributions to CIE XYZ tristimulus values using the specified colour matching functions and illuminant.
sd_to_XYZ_integration(sd[, cmfs, ...])	Convert the specified spectral distribution to CIE XYZ tristimulus values using the specified colour matching functions and illuminant using the classical integration method.

Spectral Bandpass Dependence Correction

colour

bandpass_correction(sd[, method])	Apply spectral bandpass dependence correction to the specified spectral distribution.
BANDPASS_CORRECTION_METHODS	Supported spectral bandpass dependence correction methods.

Stearns and Stearns (1988)

colour.colorimetry

bandpass_correction_Stearns1988(sd)

Apply spectral bandpass dependence correction to the specified spectral distribution using Stearns and Stearns (1988) method.

Colour Matching Functions

colour.colorimetry

LMS_ConeFundamentals([data, domain, labels])	Define a container for Stockman and Sharpe LMS cone fundamentals colour matching functions.
RGB_ColourMatchingFunctions([data, domain, ...])	Define a container for CIE RGB colour matching functions.
XYZ_ColourMatchingFunctions([data, domain, ...])	Define a container for CIE Standard Observers XYZ colour matching functions.

Dataset

colour

MSDS_CMFS

Multi-spectral distributions of the colour matching functions.

Ancillary Objects

colour.colorimetry

MSDS_CMFS_LMS	Multi-spectral distributions of the LMS colour matching functions.
MSDS_CMFS_RGB	Multi-spectral distributions of the RGB colour matching functions.
MSDS_CMFS_STANDARD_OBSERVER	Multi-spectral distributions of the CIE Standard Observer colour matching functions.

Colour Matching Functions Transformations

Ancillary Objects

colour.colorimetry

LMS_10_degree_cmfs_to_XYZ_10_degree_cmfs(...)	Convert the Stockman & Sharpe 10 Degree Cone Fundamentals colour matching functions to the CIE 2015 10 Degree Standard Observer colour matching functions.
LMS_2_degree_cmfs_to_XYZ_2_degree_cmfs(...)	Convert the Stockman & Sharpe 2 Degree Cone Fundamentals colour matching functions to the CIE 2015 2 Degree Standard Observer colour matching functions.
RGB_10_degree_cmfs_to_LMS_10_degree_cmfs(...)	Convert the Stiles & Burch 1959 10 Degree RGB CMFs colour matching functions to the Stockman & Sharpe 10 Degree Cone Fundamentals spectral sensitivity functions.
RGB_10_degree_cmfs_to_XYZ_10_degree_cmfs(...)	Convert the Stiles & Burch 1959 10 Degree RGB CMFs colour matching functions to the CIE 1964 10 Degree Standard Observer colour matching functions.
RGB_2_degree_cmfs_to_XYZ_2_degree_cmfs(...)	Convert the Wright & Guild 1931 2 Degree RGB CMFs colour matching functions to the CIE 1931 2 Degree Standard Observer colour matching functions.

Illuminants and Light Sources

Dataset

colour

CCS_ILLUMINANTS	Chromaticity coordinates of the illuminants.
CCS_LIGHT_SOURCES	Chromaticity coordinates of the light sources.
SDS_ILLUMINANTS	Spectral distributions of the illuminants.
SDS_LIGHT_SOURCES	Spectral distributions of the light sources.
TVS_ILLUMINANTS	CIE XYZ tristimulus values of the illuminants.
TVS_ILLUMINANTS_HUNTERLAB	CIE XYZ tristimulus values of the HunterLab illuminants.

Ancillary Objects

colour.colorimetry

SDS_BASIS_FUNCTIONS_CIE_ILLUMINANT_D_SERIES

CIE Illuminant D Series \(S_n(\lambda)\) basis function spectral distributions.

Dominant Wavelength and Purity

colour

colorimetric_purity(xy, xy_n[, cmfs])	Compute the colorimetric purity \(P_c\) for the specified colour stimulus \(xy\).
complementary_wavelength(xy, xy_n[, cmfs])	Compute the complementary wavelength \(\lambda_c\) for the specified colour stimulus \(xy\) and the related \(xy_wl\) first and \(xy_{cw}\) second intersection coordinates with the spectral locus.
dominant_wavelength(xy, xy_n[, cmfs, inverse])	Compute the dominant wavelength \(\lambda_d\) for colour stimulus \(xy\) and the related \(xy_wl\) first and \(xy_{cw}\) second intersection coordinates with the spectral locus.
excitation_purity(xy, xy_n[, cmfs])	Compute the excitation purity \(P_e\) for the specified colour stimulus \(xy\).

Luminous Efficiency Functions

colour

luminous_efficacy(sd[, lef])	Compute the luminous efficacy in \(lm\cdot W^{-1}\) of the specified spectral distribution using the specified luminous efficiency function.
luminous_efficiency(sd[, lef])	Compute the luminous efficiency of the specified spectral distribution using specified luminous efficiency function.
luminous_flux(sd[, lef, K_m])	Compute the luminous flux for the specified spectral distribution using the specified luminous efficiency function.
sd_mesopic_luminous_efficiency_function(L_p)	Return the mesopic luminous efficiency function \(V_m(\lambda)\) for the specified photopic luminance \(L_p\).

Dataset

colour

SDS_LEFS

Spectral distributions of the luminous efficiency functions.

Ancillary Objects

colour.colorimetry

SDS_LEFS_PHOTOPIC	Spectral distributions of the photopic luminous efficiency functions.
SDS_LEFS_SCOTOPIC	Spectral distributions of the scotopic luminous efficiency functions.

Spectral Uniformity

colour

spectral_uniformity(sds[, ...])

Compute the spectral uniformity (or spectral flatness) of the specified spectral distributions.

Lightness Computation

colour

lightness(Y[, method])	Compute the lightness \(L\) from the specified luminance \(Y\).
LIGHTNESS_METHODS	Supported lightness computation methods.

Glasser, Mckinney, Reilly and Schnelle (1958)

colour.colorimetry

lightness_Glasser1958(Y)

Compute lightness \(L\) from the specified luminance \(Y\) using the Glasser et al. (1958) method.

Wyszecki (1963)

colour.colorimetry

lightness_Wyszecki1963(Y)

Compute lightness \(W\) from the specified luminance \(Y\) using the Wyszecki (1963) method.

CIE 1976

colour.colorimetry

intermediate_lightness_function_CIE1976(Y[, Y_n])	Compute the intermediate value \(f(Y/Y_n)\) from the specified luminance \(Y\) using the specified reference white luminance \(Y_n\) as per CIE 1976 recommendation.
lightness_CIE1976(Y[, Y_n])	Compute the lightness \(L^*\) of the specified luminance \(Y\) using the specified reference white luminance \(Y_n\) as per CIE 1976 recommendation.

Fairchild and Wyble (2010)

colour.colorimetry

lightness_Fairchild2010(Y[, epsilon])

Compute lightness \(L_{hdr}\) from the specified luminance \(Y\) using Fairchild and Wyble (2010) method according to Michaelis-Menten kinetics.

Fairchild and Chen (2011)

colour.colorimetry

lightness_Fairchild2011(Y[, epsilon, method])

Compute lightness \(L_{hdr}\) from the specified luminance \(Y\) using Fairchild and Chen (2011) method according to Michaelis-Menten kinetics.

Abebe, Pouli, Larabi and Reinhard (2017)

colour.colorimetry

lightness_Abebe2017(Y[, Y_n, method])

Compute lightness \(L\) from the specified luminance \(Y\) using Abebe, Pouli, Larabi and Reinhard (2017) adaptive method for high-dynamic-range imaging according to Michaelis-Menten kinetics or Stevens's Power Law.

Luminance Computation

colour

luminance(LV[, method])	Compute the luminance \(Y\) from the specified lightness \(L^*\) or Munsell value \(V\).
LUMINANCE_METHODS	Supported luminance computation methods.

Newhall, Nickerson and Judd (1943)

colour.colorimetry

luminance_Newhall1943(V)

Compute the luminance \(R_Y\) from the specified Munsell value \(V\) using Newhall et al. (1943) method.

CIE 1976

colour.colorimetry

intermediate_luminance_function_CIE1976(f_Y_Y_n)	Compute luminance \(Y\) from the specified intermediate value \(f(Y/Y_n)\) using the specified reference white luminance \(Y_n\) as per CIE 1976 recommendation.
luminance_CIE1976(L_star[, Y_n])	Compute the luminance \(Y\) from the specified lightness \(L^*\) with the specified reference white luminance \(Y_n\).

ASTM D1535-08e1

colour.colorimetry

luminance_ASTMD1535(V)

Compute luminance \(Y\) from the specified Munsell value \(V\) using ASTM D1535-08e1 method.

Fairchild and Wyble (2010)

colour.colorimetry

luminance_Fairchild2010(L_hdr[, epsilon])

Compute luminance \(Y\) from the specified lightness \(L_{hdr}\) using Fairchild and Wyble (2010) method according to Michaelis-Menten kinetics.

Fairchild and Chen (2011)

colour.colorimetry

luminance_Fairchild2011(L_hdr[, epsilon, method])

Compute luminance \(Y\) from the specified lightness \(L_{hdr}\) using Fairchild and Chen (2011) method according to Michaelis-Menten kinetics.

Whiteness Computation

colour

whiteness(XYZ, XYZ_0[, method])	Compute the whiteness index \(W\) of the specified sample CIE XYZ tristimulus values using the specified method.
WHITENESS_METHODS	Supported whiteness computation methods.

Berger (1959)

colour.colorimetry

whiteness_Berger1959(XYZ, XYZ_0)

Compute the whiteness index \(WI\) of the specified sample CIE XYZ tristimulus values using the Berger (1959) method.

Taube (1960)

colour.colorimetry

whiteness_Taube1960(XYZ, XYZ_0)

Compute the whiteness index \(WI\) of the specified sample CIE XYZ tristimulus values using the Taube (1960) method.

Stensby (1968)

colour.colorimetry

whiteness_Stensby1968(Lab)

Compute the whiteness index \(WI\) of the specified sample CIE L*a*b* colourspace array using the Stensby (1968) method.

ASTM E313

colour.colorimetry

whiteness_ASTME313(XYZ)

Compute the whiteness index \(WI\) of the specified sample CIE XYZ tristimulus values using the ASTM E313 method.

Ganz and Griesser (1979)

colour.colorimetry

whiteness_Ganz1979(xy, Y)

Compute the whiteness index \(W\) and tint \(T\) of the specified sample CIE xy chromaticity coordinates using the Ganz and Griesser (1979) method.

CIE 2004

colour.colorimetry

whiteness_CIE2004(xy, Y, xy_n[, observer])

Compute the whiteness \(W\) or \(W_{10}\) and tint \(T\) or \(T_{10}\) of the specified sample CIE xy chromaticity coordinates using the CIE 2004 method.

Yellowness Computation

colour

yellowness(XYZ[, method])	Compute the yellowness index \(YI\) using the specified method.
YELLOWNESS_METHODS	Supported yellowness computation methods.

ASTM D1925

colour.colorimetry

yellowness_ASTMD1925(XYZ)

Compute the yellowness index \(YI\) of the specified sample CIE XYZ tristimulus values using the ASTM D1925 method.

ASTM E313

colour.colorimetry

yellowness_ASTME313(XYZ[, C_XZ])	Compute the yellowness index \(YI\) of the specified sample CIE XYZ tristimulus values using the ASTM E313 method.
yellowness_ASTME313_alternative(XYZ)	Compute the yellowness index \(YI\) of the specified sample CIE XYZ tristimulus values using the alternative ASTM E313 method.
YELLOWNESS_COEFFICIENTS_ASTME313	Coefficients \(C_X\) and \(C_Z\) for the ASTM E313 yellowness index \(YI\) computation method.