colour.models.hunter_lab Module¶
Hunter L,a,b Colour Scale¶
Defines the Hunter L,a,b colour scale transformations:
References
[1] | HunterLab. (2008). Hunter L,a,b Color Scale. Retrieved from http://www.hunterlab.se/wp-content/uploads/2012/11/Hunter-L-a-b.pdf |
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colour.models.hunter_lab.
XYZ_to_K_ab_HunterLab1966
(XYZ)[source]¶ Converts from whitepoint CIE XYZ tristimulus values to Hunter L,a,b \(K_{a}\) and \(K_{b}\) chromaticity coefficients.
Parameters: XYZ (array_like) – Whitepoint CIE XYZ tristimulus values. Returns: Hunter L,a,b \(K_{a}\) and \(K_{b}\) chromaticity coefficients. Return type: ndarray Notes
- Input CIE XYZ tristimulus values are in domain [0, 100].
References
[2] HunterLab. (2008). Illuminant Factors in Universal Software and EasyMatch Coatings. Retrieved from https://support.hunterlab.com/hc/en-us/article_attachments/201437785/an02_02.pdf Examples
>>> XYZ = np.array([109.850, 100.000, 35.585]) >>> XYZ_to_K_ab_HunterLab1966(XYZ) array([ 185.2378721..., 38.4219142...])
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colour.models.hunter_lab.
XYZ_to_Hunter_Lab
(XYZ, XYZ_n=(96.38, 100.0, 82.45), K_ab=(173.51, 58.48))[source]¶ Converts from CIE XYZ tristimulus values to Hunter L,a,b colour scale.
Parameters: - XYZ (array_like) – CIE XYZ tristimulus values.
- XYZ_n (array_like, optional) – Reference illuminant tristimulus values.
- K_ab (array_like, optional) – Reference illuminant chromaticity coefficients, if K_ab is set to
None it will be computed using
XYZ_to_K_ab_HunterLab1966()
.
Returns: Hunter L,a,b colour scale array.
Return type: ndarray
Notes
- Input CIE XYZ and reference illuminant tristimulus values are in domain [0, 100].
- Output Lightness \(L^*\) is in range [0, 100].
Examples
>>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313]) * 100 >>> D50 = HUNTERLAB_ILLUMINANTS.get( ... 'CIE 1931 2 Degree Standard Observer').get('D50') >>> XYZ_to_Hunter_Lab(XYZ, D50.XYZ_n, D50.K_ab) array([ 31.7490157..., -15.1146262..., -2.7866075...])
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colour.models.hunter_lab.
Hunter_Lab_to_XYZ
(Lab, XYZ_n=(96.38, 100.0, 82.45), K_ab=(173.51, 58.48))[source]¶ Converts from Hunter L,a,b colour scale to CIE XYZ tristimulus values.
Parameters: - Lab (array_like) – Hunter L,a,b colour scale array.
- XYZ_n (array_like, optional) – Reference illuminant tristimulus values.
- K_ab (array_like, optional) – Reference illuminant chromaticity coefficients, if K_ab is set to
None it will be computed using
XYZ_to_K_ab_HunterLab1966()
.
Returns: CIE XYZ tristimulus values.
Return type: ndarray
Notes
- Input Lightness \(L^*\) is in domain [0, 100].
- Input CIE XYZ and reference illuminant tristimulus values are in domain [0, 100].
- Output CIE XYZ tristimulus values are in range [0, 100].
Examples
>>> Lab = np.array([31.74901573, -15.11462629, -2.78660758]) >>> D50 = HUNTERLAB_ILLUMINANTS.get( ... 'CIE 1931 2 Degree Standard Observer').get('D50') >>> Hunter_Lab_to_XYZ(Lab, D50.XYZ_n, D50.K_ab) array([ 7.049534, 10.08 , 9.558313])