colour.spectral_uniformity#

colour.spectral_uniformity(sds: Sequence[SpectralDistribution | MultiSpectralDistributions] | SpectralDistribution | MultiSpectralDistributions, use_second_order_derivatives: bool = False) → NDArrayFloat[source]#

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

Spectral uniformity \((r')^2\) is computed as follows:

\(mean((r'_1)^2, (r'_2)^2, ..., (r'_n)^2)\)

where \((r'_i)^2\) is the first-order derivative, squared, of the reflectance \(r_i\) of a test sample.

Parameters:

sds (Sequence[SpectralDistribution | MultiSpectralDistributions] | SpectralDistribution | MultiSpectralDistributions) – Spectral distributions or multi-spectral distributions to compute the spectral uniformity of. sds can be a single colour.MultiSpectralDistributions class instance, a list of colour.MultiSpectralDistributions class instances or a List of colour.SpectralDistribution class instances.
use_second_order_derivatives (bool) – Whether to use the second-order derivatives in the computations.

Returns:

Spectral uniformity.

Return type:

numpy.ndarray

Warning

The spectral distributions must have the same spectral shape.

References

[DFH+15]

Examples

>>> from colour.quality.datasets import SDS_TCS
>>> spectral_uniformity(SDS_TCS.values())  
array([  9.5514285...e-06,   1.1482142...e-05,   1.8784285...e-05,
         2.8711428...e-05,   3.1971428...e-05,   3.2342857...e-05,
         3.3850000...e-05,   3.9925714...e-05,   4.1333571...e-05,
         2.4002142...e-05,   5.7621428...e-06,   1.4757142...e-06,
         9.7928571...e-07,   2.0057142...e-06,   3.7157142...e-06,
         5.7678571...e-06,   7.5557142...e-06,   7.4635714...e-06,
         5.7492857...e-06,   3.8692857...e-06,   3.5407142...e-06,
         4.4742857...e-06,   5.6435714...e-06,   7.6371428...e-06,
         1.0171428...e-05,   1.2254285...e-05,   1.4810000...e-05,
         1.6517142...e-05,   1.5430714...e-05,   1.4536428...e-05,
         1.4037857...e-05,   1.1587857...e-05,   1.0743571...e-05,
         1.0979285...e-05,   1.0398571...e-05,   8.2971428...e-06,
         6.3057142...e-06,   5.0942857...e-06,   4.8500000...e-06,
         5.5371428...e-06,   6.4128571...e-06,   7.2592857...e-06,
         7.7750000...e-06,   7.1607142...e-06,   6.6635714...e-06,
         6.7328571...e-06,   7.5307142...e-06,   1.0733571...e-05,
         1.6234285...e-05,   2.2570714...e-05,   2.7056428...e-05,
         2.7781428...e-05,   2.5025714...e-05,   1.7966428...e-05,
         1.0505000...e-05,   5.9657142...e-06,   3.6421428...e-06,
         2.1664285...e-06,   1.2935714...e-06,   8.3642857...e-07,
         7.2500000...e-07,   6.3928571...e-07,   6.6285714...e-07,
         8.5571428...e-07,   1.4507142...e-06,   2.2542857...e-06,
         3.4142857...e-06,   4.9864285...e-06,   6.4907142...e-06,
         7.8928571...e-06,   9.1664285...e-06,   9.9521428...e-06,
         9.7664285...e-06,   9.3150000...e-06,   8.9092857...e-06,
         8.1578571...e-06,   6.8935714...e-06,   5.5721428...e-06,
         4.4592857...e-06,   3.4778571...e-06,   2.7650000...e-06,
         2.3114285...e-06,   1.7092857...e-06,   1.1771428...e-06,
         9.8428571...e-07,   8.8285714...e-07,   7.4142857...e-07,
         7.0142857...e-07,   7.0857142...e-07,   6.6642857...e-07,
         7.5928571...e-07,   8.7000000...e-07,   8.2714285...e-07,
         7.1714285...e-07,   6.6000000...e-07])