colour.delta_E#

colour.delta_E(a: ArrayLike, b: ArrayLike, method: LiteralDeltaEMethod | str = 'CIE 2000', *, additional_data: Literal[False] = False, **kwargs: Any) → NDArrayFloat[source]#

colour.delta_E(a: ArrayLike, b: ArrayLike, method: LiteralDeltaEMethod | str = 'CIE 2000', *, additional_data: bool, **kwargs: Any) → NDArrayFloat | DeltaE_Specification

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

Parameters:

a (ArrayLike) – CIE L*a*b*, \(IC_TC_P\), or \(J'a'b'\) colourspace array \(a\).
b (ArrayLike) – CIE L*a*b*, \(IC_TC_P\), or \(J'a'b'\) colourspace array \(b\).
method (LiteralDeltaEMethod | str) – Computation method.
additional_data (bool) – Whether to output additional data.
c – {colour.difference.delta_E_CMC()}, Chroma weighting factor.
l – {colour.difference.delta_E_CMC()}, Lightness weighting factor.
textiles – {colour.difference.delta_E_CIE1994(), colour.difference.delta_E_CIE2000(), colour.difference.delta_E_DIN99()}, Textiles application specific parametric factors \(k_L=2,\ k_C=k_H=1,\ k_1=0.048,\ k_2=0.014,\ k_E=2,\ k_{CH}=0.5\) weights are used instead of \(k_L=k_C=k_H=1,\ k_1=0.045,\ k_2=0.015,\ k_E=k_{CH}=1.0\).
kwargs (Any) –
See the documentation of the available \(\Delta E_{ab}\) definitions.

Arguments for the \(\Delta E_{ab}\) definitions are passed as keyword arguments whose names are those of the \(\Delta E_{ab}\) definitions and values set as dictionaries. For example, when computing \(\Delta E_{DIN99}\), passing arguments to the colour.delta_E_DIN99() definition is done as follows:
```
delta_E(
    a,
    b,
    "DIN99",
    delta_E_DIN99={"method": "DIN99b"},
)
```
It is also possible to pass keyword arguments directly, but this is dangerous and could cause unexpected behaviour. For example:
```
delta_E(
    a,
    b,
    "DIN99",
    method="DIN99b",
)
```
Because both the colour.delta_E() and colour.delta_E_DIN99() definitions have a method argument, this will raise an exception in the colour.delta_E() definition.

Returns:

Colour difference \(\Delta E_{ab}\). When additional_data=True, a specification dataclass is returned containing the colour difference dE and additional component-wise colour difference terms depending on the selected method.

Return type:

numpy.ndarray or DeltaE_Specification

References

[ASTMInternational07], [InternationalTUnion19], [LLW+17], [Lin03a], [Lin11], [Lin09b], [LCL06], [Mel13], [Wikipedia08a]

Examples

>>> import numpy as np
>>> a = np.array([48.99183622, -0.10561667, 400.65619925])
>>> b = np.array([50.65907324, -0.11671910, 402.82235718])
>>> delta_E(a, b)
np.float64(1.6709303...)
>>> delta_E(a, b, method="CIE 2000")
np.float64(1.6709303...)
>>> delta_E(a, b, method="CIE 1976")
np.float64(2.7335037...)
>>> delta_E(a, b, method="CIE 1994")
np.float64(1.6711191...)
>>> delta_E(a, b, method="CIE 1994", textiles=True)
...
np.float64(0.8404677...)
>>> delta_E(a, b, method="DIN99")
np.float64(1.5591089...)
>>> a = np.array([0.4885468072, -0.04739350675, 0.07475401302])
>>> b = np.array([0.4899203231, -0.04567508203, 0.07361341775])
>>> delta_E(a, b, method="ITP")
np.float64(1.42657228...)
>>> a = np.array([54.90433134, -0.08450395, -0.06854831])
>>> b = np.array([54.90433134, -0.08442362, -0.06848314])
>>> delta_E(a, b, method="CAM02-UCS")
np.float64(0.0001034...)
>>> delta_E(a, b, method="CAM16-LCD")
np.float64(0.0001034...)
>>> a = np.array([39.91531343, 51.16658481, 146.12933781])
>>> b = np.array([53.12207516, -39.92365056, 249.54831278])
>>> delta_E(a, b, method="HyAB")
np.float64(151.0215481...)
>>> a = np.array([39.91531343, 51.16658481, 146.12933781])
>>> b = np.array([53.12207516, -39.92365056, 249.54831278])
>>> delta_E(a, b, method="HyCH")
np.float64(48.66427941...)

colour.delta_E#

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