Source code for colour.recovery.smits1999

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
Smits (1999) - Reflectance Recovery
===================================

Defines objects for reflectance recovery using *Smits (1999)* method.

See Also
--------
`Smits (1999) - Reflectance Recovery Jupyter Notebook
<http://nbviewer.jupyter.org/github/colour-science/colour-notebooks/\
blob/master/notebooks/recovery/smits1999.ipynb>`_

References
----------
.. [1]  Smits, B. (1999). An RGB-to-Spectrum Conversion for Reflectances.
        Journal of Graphics Tools, 4(4), 11–22.
        doi:10.1080/10867651.1999.10487511
"""

from __future__ import division, unicode_literals

import numpy as np

from colour.colorimetry import ILLUMINANTS, zeros_spd
from colour.models import (XYZ_to_RGB, normalised_primary_matrix,
                           sRGB_COLOURSPACE)
from colour.recovery import SMITS_1999_SPDS

__author__ = 'Colour Developers'
__copyright__ = 'Copyright (C) 2013-2017 - Colour Developers'
__license__ = 'New BSD License - http://opensource.org/licenses/BSD-3-Clause'
__maintainer__ = 'Colour Developers'
__email__ = '[email protected]'
__status__ = 'Production'

__all__ = [
    'SMITS1999_PRIMARIES', 'SMITS1999_WHITEPOINT',
    'SMITS1999_XYZ_TO_RGB_MATRIX', 'XYZ_to_RGB_Smits1999',
    'RGB_to_spectral_Smits1999'
]

SMITS1999_PRIMARIES = sRGB_COLOURSPACE.primaries
"""
Current *Smits (1999)* method implementation colourspace primaries.

SMITS1999_PRIMARIES : ndarray, (3, 2)
"""

SMITS1999_WHITEPOINT = (
    ILLUMINANTS['CIE 1931 2 Degree Standard Observer']['E'])
"""
Current *Smits (1999)* method implementation colourspace whitepoint.

SMITS1999_WHITEPOINT : ndarray
"""

SMITS1999_XYZ_TO_RGB_MATRIX = np.linalg.inv(
    normalised_primary_matrix(SMITS1999_PRIMARIES, SMITS1999_WHITEPOINT))
"""
Current *Smits (1999)* method implementation *RGB* colourspace to
*CIE XYZ* tristimulus values matrix.

SMITS1999_XYZ_TO_RGB_MATRIX : array_like, (3, 3)
"""


[docs]def XYZ_to_RGB_Smits1999(XYZ, chromatic_adaptation_transform='Bradford'): """ Convenient object to convert from *CIE XYZ* tristimulus values to *RGB* colourspace in conditions required by the current *Smits (1999)* method implementation. Parameters ---------- XYZ : array_like *CIE XYZ* tristimulus values. chromatic_adaptation_transform : unicode, optional **{'CAT02', 'XYZ Scaling', 'Von Kries', 'Bradford', 'Sharp', 'Fairchild', 'CMCCAT97', 'CMCCAT2000', 'CAT02_BRILL_CAT', 'Bianco', 'Bianco PC'}**, *Chromatic adaptation* method. Returns ------- ndarray *RGB* colour array. Notes ----- - Input *CIE XYZ* tristimulus values are in domain [0, 1]. Examples -------- >>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313]) >>> XYZ_to_RGB_Smits1999(XYZ) # doctest: +ELLIPSIS array([ 0.0214496..., 0.1315460..., 0.0928760...]) """ return XYZ_to_RGB( XYZ, SMITS1999_WHITEPOINT, SMITS1999_WHITEPOINT, SMITS1999_XYZ_TO_RGB_MATRIX, chromatic_adaptation_transform, encoding_cctf=None)
[docs]def RGB_to_spectral_Smits1999(RGB): """ Recovers the spectral power distribution of given *RGB* colourspace array using *Smits (1999)* method. Parameters ---------- RGB : array_like, (3,) *RGB* colourspace array. Returns ------- SpectralPowerDistribution Recovered spectral power distribution. Examples -------- >>> RGB = np.array([0.02144962, 0.13154603, 0.09287601]) >>> print(RGB_to_spectral_Smits1999(RGB)) # doctest: +ELLIPSIS SpectralPowerDistribution('Smits (1999) - \ [ 0.02144962 0.13154603 0.09287601]', (380.0, 720.0, 37.7777777...)) """ white_spd = SMITS_1999_SPDS['white'].clone() cyan_spd = SMITS_1999_SPDS['cyan'].clone() magenta_spd = SMITS_1999_SPDS['magenta'].clone() yellow_spd = SMITS_1999_SPDS['yellow'].clone() red_spd = SMITS_1999_SPDS['red'].clone() green_spd = SMITS_1999_SPDS['green'].clone() blue_spd = SMITS_1999_SPDS['blue'].clone() R, G, B = np.ravel(RGB) spd = zeros_spd(SMITS_1999_SPDS['white'].shape) spd.name = 'Smits (1999) - {0}'.format(RGB) if R <= G and R <= B: spd += white_spd * R if G <= B: spd += cyan_spd * (G - R) spd += blue_spd * (B - G) else: spd += cyan_spd * (B - R) spd += green_spd * (G - B) elif G <= R and G <= B: spd += white_spd * G if R <= B: spd += magenta_spd * (R - G) spd += blue_spd * (B - R) else: spd += magenta_spd * (B - G) spd += red_spd * (R - B) else: spd += white_spd * B if R <= G: spd += yellow_spd * (R - B) spd += green_spd * (G - R) else: spd += yellow_spd * (G - B) spd += red_spd * (R - G) return spd