colour.colorimetry.yellowness Module¶
Yellowness Index \(Y\)¶
Defines yellowness index \(Y\) computation objects:
See also
References
[1]  (1, 2) XRite, & Pantone. (2012). Color iQC and Color iMatch Color Calculations Guide. Retrieved from http://www.xrite.com/documents/literature/en/09_Color_Calculations_en.pdf 

colour.colorimetry.yellowness.
yellowness_ASTMD1925
(XYZ)[source]¶ Returns the yellowness index \(YI\) of given sample CIE XYZ tristimulus values using ASTM D1925 method. [1]
ASTM D1925 has been specifically developed for the definition of the Yellowness of homogeneous, nonfluorescent, almost neutraltransparent, whitescattering or opaque plastics as they will be reviewed under daylight condition. It can be other materials as well, as long as they fit into this description.
Parameters: XYZ (array_like) – CIE XYZ tristimulus values of sample. Returns: Whiteness \(YI\). Return type: numeric or ndarray Notes
 Input CIE XYZ tristimulus values are in domain [0, 100].
Warning
The input domain of that definition is non standard!
Examples
>>> import numpy as np >>> XYZ = np.array([95.00000000, 100.00000000, 105.00000000]) >>> yellowness_ASTMD1925(XYZ) 10.2999999...

colour.colorimetry.yellowness.
yellowness_ASTME313
(XYZ)[source]¶ Returns the yellowness index \(YI\) of given sample CIE XYZ tristimulus values using ASTM E313 method. [1]
ASTM E313 has successfully been used for a variety of white or near white materials. This includes coatings, Plastics, Textiles.
Parameters: XYZ (array_like) – CIE XYZ tristimulus values of sample. Returns: Whiteness \(YI\). Return type: numeric or ndarray Notes
 Input CIE XYZ tristimulus values are in domain [0, 100].
Warning
The input domain of that definition is non standard!
Examples
>>> import numpy as np >>> XYZ = np.array([95.00000000, 100.00000000, 105.00000000]) >>> yellowness_ASTME313(XYZ) 11.0650000...

colour.colorimetry.yellowness.
YELLOWNESS_METHODS
= CaseInsensitiveMapping({u'ASTM E313': <function yellowness_ASTME313>, u'ASTM D1925': <function yellowness_ASTMD1925>})¶ Supported yellowness computations methods.
 YELLOWNESS_METHODS : CaseInsensitiveMapping
 {‘ASTM E313’, ‘ASTM D1925’}

colour.colorimetry.yellowness.
yellowness
(XYZ, method=u'ASTM E313')[source]¶ Returns the yellowness \(W\) using given method.
Parameters:  XYZ (array_like) – CIE XYZ tristimulus values of sample.
 method (unicode, optional) – {‘ASTM E313’, ‘ASTM D1925’}, Computation method.
Returns: yellowness \(Y\).
Return type: numeric or ndarray
Examples
>>> import numpy as np >>> XYZ = np.array([95.00000000, 100.00000000, 105.00000000]) >>> yellowness(XYZ) 11.0650000... >>> method = 'ASTM D1925' >>> yellowness(XYZ, method=method) 10.2999999...