Source code for colour.volume.macadam_limits

# -*- coding: utf-8 -*-
"""
Optimal Colour Stimuli - MacAdam Limits
=======================================

Defines objects related to *Optimal Colour Stimuli* computations.
"""

from __future__ import division, unicode_literals

import numpy as np
from scipy.spatial import Delaunay

from colour.models import xyY_to_XYZ
from colour.volume import ILLUMINANT_OPTIMAL_COLOUR_STIMULI

__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2020 - Colour Developers'
__license__ = 'New BSD License - https://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = 'colour-developers@colour-science.org'
__status__ = 'Production'

__all__ = ['is_within_macadam_limits']

_XYZ_OPTIMAL_COLOUR_STIMULI_CACHE = {}
_XYZ_OPTIMAL_COLOUR_STIMULI_TRIANGULATIONS_CACHE = {}


def _XYZ_optimal_colour_stimuli(illuminant):
    """
    Returns given illuminant *Optimal Colour Stimuli* in *CIE XYZ* tristimulus
    values and caches it if not existing.

    Parameters
    ----------
    illuminant : unicode
        Illuminant.

    Returns
    -------
    tuple
        Illuminant *Optimal Colour Stimuli*.
    """

    optimal_colour_stimuli = ILLUMINANT_OPTIMAL_COLOUR_STIMULI.get(illuminant)
    if optimal_colour_stimuli is None:
        raise KeyError('"{0}" not found in factory '
                       '"Optimal Colour Stimuli": "{1}".'.format(
                           illuminant,
                           sorted(ILLUMINANT_OPTIMAL_COLOUR_STIMULI.keys())))

    vertices = _XYZ_OPTIMAL_COLOUR_STIMULI_CACHE.get(illuminant)
    if vertices is None:
        _XYZ_OPTIMAL_COLOUR_STIMULI_CACHE[illuminant] = vertices = (
            xyY_to_XYZ(optimal_colour_stimuli) / 100)
    return vertices


[docs]def is_within_macadam_limits(xyY, illuminant, tolerance=None): """ Returns if given *CIE xyY* colourspace array is within MacAdam limits of given illuminant. Parameters ---------- xyY : array_like *CIE xyY* colourspace array. illuminant : unicode Illuminant. tolerance : numeric, optional Tolerance allowed in the inside-triangle check. Returns ------- bool Is within MacAdam limits. Notes ----- +------------+-----------------------+---------------+ | **Domain** | **Scale - Reference** | **Scale - 1** | +============+=======================+===============+ | ``xyY`` | [0, 1] | [0, 1] | +------------+-----------------------+---------------+ Examples -------- >>> is_within_macadam_limits(np.array([0.3205, 0.4131, 0.51]), 'A') array(True, dtype=bool) >>> a = np.array([[0.3205, 0.4131, 0.51], ... [0.0005, 0.0031, 0.001]]) >>> is_within_macadam_limits(a, 'A') array([ True, False], dtype=bool) """ optimal_colour_stimuli = _XYZ_optimal_colour_stimuli(illuminant) triangulation = _XYZ_OPTIMAL_COLOUR_STIMULI_TRIANGULATIONS_CACHE.get( illuminant) if triangulation is None: _XYZ_OPTIMAL_COLOUR_STIMULI_TRIANGULATIONS_CACHE[illuminant] = \ triangulation = Delaunay(optimal_colour_stimuli) simplex = triangulation.find_simplex(xyY_to_XYZ(xyY), tol=tolerance) simplex = np.where(simplex >= 0, True, False) return simplex