Colour Difference

Delta E

colour

delta_E(...)	Compute the colour difference \(\Delta E_{ab}\) between two specified CIE L*a*b*, \(IC_TC_P\), or \(J'a'b'\) colourspace arrays.
DELTA_E_METHODS	Supported \(\Delta E_{ab}\) colour difference computation methods.

CIE 1976

colour.difference

delta_E_CIE1976(-> NDArrayFloat)	Compute the colour difference \(\Delta E_{76}\) between two specified CIE L*a*b* colourspace arrays using the CIE 1976 recommendation.
JND_CIE1976	Just Noticeable Difference (JND) according to CIE 1976 colour difference formula, i.e., Euclidean distance in CIE L*a*b* colourspace.

CIE 1994

colour.difference

delta_E_CIE1994(-> NDArrayFloat)

Compute the colour difference \(\Delta E_{94}\) between two specified CIE L*a*b* colourspace arrays using the CIE 1994 recommendation.

CIE 2000

colour.difference

delta_E_CIE2000(-> NDArrayFloat)

Compute the colour difference \(\Delta E_{00}\) between two specified CIE L*a*b* colourspace arrays using the CIE 2000 recommendation.

CMC

colour.difference

delta_E_CMC(-> NDArrayFloat)

Compute the colour difference \(\Delta E_{CMC}\) between two specified CIE L*a*b* colourspace arrays using the Colour Measurement Committee recommendation.

ITP

colour.difference

delta_E_ITP(-> NDArrayFloat)

Compute the colour difference \(\Delta E_{ITP}\) between two specified \(IC_TC_P\) colour encoding arrays using the Recommendation ITU-R BT.2124.

Luo, Cui and Li (2006)

colour.difference

delta_E_CAM02LCD(-> NDArrayFloat)	Compute the colour difference \(\Delta E'\) between two specified CAM02-LCD colourspace \(J'a'b'\) arrays using the Luo et al. (2006) formula.
delta_E_CAM02SCD(-> NDArrayFloat)	Compute the colour difference \(\Delta E'\) between two specified CAM02-SCD colourspace \(J'a'b'\) arrays using the Luo et al. (2006) formula.
delta_E_CAM02UCS(-> NDArrayFloat)	Compute the colour difference \(\Delta E'\) between two specified CAM02-UCS colourspace \(J'a'b'\) arrays using the Luo et al. (2006) formula.

Li, Li, Wang, Zu, Luo, Cui, Melgosa, Brill and Pointer (2017)

colour.difference

delta_E_CAM16LCD(Jpapbp_1, Jpapbp_2[, ...])	Compute the colour difference \(\Delta E'\) between two specified CAM16-LCD colourspace \(J'a'b'\) arrays using the Li et al. (2017) formula.
delta_E_CAM16SCD(Jpapbp_1, Jpapbp_2[, ...])	Compute the colour difference \(\Delta E'\) between two specified CAM16-SCD colourspace \(J'a'b'\) arrays using the Li et al. (2017) formula.
delta_E_CAM16UCS(Jpapbp_1, Jpapbp_2[, ...])	Compute the colour difference \(\Delta E'\) between two specified CAM16-UCS colourspace \(J'a'b'\) arrays using the Li et al. (2017) formula.

DIN99

colour.difference

delta_E_DIN99(-> NDArrayFloat)

Compute the colour difference \(\Delta E_{DIN99}\) between two specified CIE L*a*b* colourspace arrays using the DIN99 formula.

HyAB

colour.difference

delta_E_HyAB(-> NDArrayFloat)

Compute the colour difference between two CIE L*a*b* colourspace arrays using a combination of a Euclidean metric in hue and chroma with a city-block metric to incorporate lightness differences.

HyCH

colour.difference

delta_E_HyCH(-> NDArrayFloat)

Compute the colour difference between two CIE L*a*b* colourspace arrays using a combination of Euclidean metric in hue and chroma with a city-block metric to incorporate lightness differences based on CIE 2000 recommendation attributes.

Standardized Residual Sum of Squares (STRESS) Index

colour

index_stress(d_E, d_V[, method])	Compute Kruskal's Standardized Residual Sum of Squares (\(STRESS\)) index using the specified method
INDEX_STRESS_METHODS	Supported Standardized Residual Sum of Squares (STRESS) index computation methods.

colour.difference

index_stress_Garcia2007(d_E, d_V)

Compute the Kruskal's Standardized Residual Sum of Squares (:math:`STRESS`) index according to the García, Huertas, Melgosa and Cui (2007) method.

Huang et al. (2015) Power-Functions

colour.difference

power_function_Huang2015(d_E[, coefficients])

Apply the Huang, Cui, Melgosa, Sanchez-Maranon, Li, Luo and Liu (2015) power-function to improve colour difference values for specified coefficients: \(d_E^{\prime}=a \cdot d_{E}^{b}\).

Metamerism

colour.difference.metamerism_index

Lab_to_metamerism_index(-> NDArrayFloat)	Compute the metamerism index \(M_{t}\) between four specified CIE L*a*b* colourspace arrays.
XYZ_to_metamerism_index(-> NDArrayFloat)	Compute the metamerism index \(M_{t}\) from four specified CIE XYZ colourspace arrays.
sd_to_metamerism_index(sd_spl, sd_std, cmfs, ...)	Compute the metamerism index \(M_t\) of a sample pair for change of illuminant using the spectral correction method as defined in ISO 18314-4:2024.