Coverage for difference/huang2015.py: 15%

1""" 

2Huang et al. (2015) Power-Functions 

3=================================== 

4 

5Define the *Huang, Cui, Melgosa, Sanchez-Maranon, Li, Luo and Liu (2015)* 

6power-functions for improving the performance of colour-difference formulas. 

7 

8- :func:`colour.difference.power_function_Huang2015` 

9 

10References 

11---------- 

12- :cite:`Huang2015` : Huang, M., Cui, G., Melgosa, M., Sanchez-Maranon, M., 

13 Li, C., Luo, M. R., & Liu, H. (2015). Power functions improving the 

14 performance of color-difference formulas. Optical Society of America, 

15 23(1), 597-610. doi:10.1364/OE.23.000597 

16- :cite:`Li2017` : Li, C., Li, Z., Wang, Z., Xu, Y., Luo, M. R., Cui, G., 

17 Melgosa, M., Brill, M. H., & Pointer, M. (2017). Comprehensive color 

18 solutions: CAM16, CAT16, and CAM16-UCS. Color Research & Application, 

19 42(6), 703-718. doi:10.1002/col.22131 

20""" 

21 

22from __future__ import annotations 

23 

24import typing 

25 

26import numpy as np 

27 

28if typing.TYPE_CHECKING: 

29 from colour.hints import ArrayLike, Literal, NDArrayFloat 

30 

31from colour.utilities import CanonicalMapping, tsplit, validate_method 

32 

33__author__ = "Colour Developers" 

34__copyright__ = "Copyright 2013 Colour Developers" 

35__license__ = "BSD-3-Clause - https://opensource.org/licenses/BSD-3-Clause" 

36__maintainer__ = "Colour Developers" 

37__email__ = "colour-developers@colour-science.org" 

38__status__ = "Production" 

39 

40__all__ = [ 

41 "power_function_Huang2015", 

42] 

43 

44COEFFICIENTS_HUANG2015: CanonicalMapping = CanonicalMapping( 

45 { 

46 "CIE 1976": np.array([1.26, 0.55]), 

47 "CIE 1994": np.array([1.41, 0.70]), 

48 "CIE 2000": np.array([1.43, 0.70]), 

49 "CMC": np.array([1.34, 0.66]), 

50 "CAM02-LCD": np.array([1.00, 0.85]), 

51 "CAM02-SCD": np.array([1.45, 0.75]), 

52 "CAM02-UCS": np.array([1.30, 0.75]), 

53 "CAM16-UCS": np.array([1.41, 0.63]), 

54 "DIN99d": np.array([1.28, 0.74]), 

55 "OSA": np.array([3.32, 0.62]), 

56 "OSA-GP-Euclidean": np.array([1.52, 0.76]), 

57 "ULAB": np.array([1.17, 0.69]), 

58 } 

59) 

60COEFFICIENTS_HUANG2015.__doc__ = """ 

61*Huang et al. (2015)* power-functions coefficients. 

62 

63References 

64---------- 

65:cite:`Huang2015`, :cite:`Li2017` 

66 

67Notes 

68----- 

69- :cite:`Li2017` does not give the coefficients for the *CAM16-LCD* and 

70 *CAM16-SCD* colourspaces. *Ronnie Luo* has been contacted to know if 

71 they have been computed. 

72 

73Aliases: 

74 

75- 'cie1976': 'CIE 1976' 

76- 'cie1994': 'CIE 1994' 

77- 'cie2000': 'CIE 2000' 

78""" 

79COEFFICIENTS_HUANG2015["cie1976"] = COEFFICIENTS_HUANG2015["CIE 1976"] 

80COEFFICIENTS_HUANG2015["cie1994"] = COEFFICIENTS_HUANG2015["CIE 1994"] 

81COEFFICIENTS_HUANG2015["cie2000"] = COEFFICIENTS_HUANG2015["CIE 2000"] 

82 

83 

84def power_function_Huang2015( 

85 d_E: ArrayLike, 

86 coefficients: ( 

87 Literal[ 

88 "CIE 1976", 

89 "CIE 1994", 

90 "CIE 2000", 

91 "CMC", 

92 "CAM02-LCD", 

93 "CAM02-SCD", 

94 "CAM16-UCS", 

95 "DIN99d", 

96 "OSA", 

97 "OSA-GP-Euclidean", 

98 "ULAB", 

99 ] 

100 | str 

101 ) = "CIE 2000", 

102) -> NDArrayFloat: 

103 """ 

104 Apply the *Huang, Cui, Melgosa, Sanchez-Maranon, Li, Luo and Liu 

105 (2015)* power-function to improve colour difference values for 

106 specified coefficients: :math:`d_E^{\\prime}=a \\cdot d_{E}^{b}`. 

107 

108 Parameters 

109 ---------- 

110 d_E 

111 Computed colour difference array :math:`\\Delta E`. 

112 coefficients 

113 Coefficients for the power-function. 

114 

115 Returns 

116 ------- 

117 :class:`numpy.ndarray` 

118 Improved :math:`\\Delta E` value. 

119 

120 References 

121 ---------- 

122 :cite:`Huang2015`, :cite:`Li2017` 

123 

124 Examples 

125 -------- 

126 >>> d_E = np.array([2.0425, 2.8615, 3.4412]) 

127 >>> power_function_Huang2015(d_E) # doctest: +ELLIPSIS 

128 array([ 2.3574879..., 2.9850503..., 3.3965106...]) 

129 """ 

130 

131 coefficients = validate_method( 

132 coefficients, 

133 tuple(COEFFICIENTS_HUANG2015), 

134 '"{0}" coefficients are invalid, they must be one of {1}!', 

135 ) 

136 

137 a, b = tsplit(COEFFICIENTS_HUANG2015[coefficients]) 

138 

139 return a * d_E**b