def get_illuminant_xyz(self, observer=None, illuminant=None):
"""
:param str observer: Get the XYZ values for another observer angle. Must
be either '2' or '10'.
:param str illuminant: Get the XYZ values for another illuminant.
:returns: the color's illuminant's XYZ values.
"""
try:
if observer is None:
observer = self.observer
illums_observer = color_constants.ILLUMINANTS[observer]
except KeyError:
raise InvalidObserverError(self)
try:
if illuminant is None:
illuminant = self.illuminant
illum_xyz = illums_observer[illuminant]
except (KeyError, AttributeError):
raise InvalidIlluminantError(illuminant)
return {'X': illum_xyz[0], 'Y': illum_xyz[1], 'Z': illum_xyz[2]}
def Spectral_to_XYZ(cobj, illuminant_override=None, *args, **kwargs):
"""
Converts spectral readings to XYZ.
"""
# If the user provides an illuminant_override numpy array, use it.
if illuminant_override:
reference_illum = illuminant_override
else:
# Otherwise, look up the illuminant from known standards based
# on the value of 'illuminant' pulled from the SpectralColor object.
try:
reference_illum = spectral_constants.REF_ILLUM_TABLE[
cobj.illuminant]
except KeyError:
raise InvalidIlluminantError(cobj.illuminant)
# Get the spectral distribution of the selected standard observer.
if cobj.observer == '10':
std_obs_x = spectral_constants.STDOBSERV_X10
std_obs_y = spectral_constants.STDOBSERV_Y10
std_obs_z = spectral_constants.STDOBSERV_Z10
else:
# Assume 2 degree, since it is theoretically the only other possibility.
std_obs_x = spectral_constants.STDOBSERV_X2
std_obs_y = spectral_constants.STDOBSERV_Y2
std_obs_z = spectral_constants.STDOBSERV_Z2
# This is a NumPy array containing the spectral distribution of the color.
sample = cobj.get_numpy_array()
# The denominator is constant throughout the entire calculation for X,
# Y, and Z coordinates. Calculate it once and re-use.
denom = std_obs_y * reference_illum
# This is also a common element in the calculation whereby the sample
# NumPy array is multiplied by the reference illuminant's power distribution
# (which is also a NumPy array).
sample_by_ref_illum = sample * reference_illum
# Calculate the numerator of the equation to find X.
x_numerator = sample_by_ref_illum * std_obs_x
y_numerator = sample_by_ref_illum * std_obs_y
z_numerator = sample_by_ref_illum * std_obs_z
xyz_x = x_numerator.sum() / denom.sum()
xyz_y = y_numerator.sum() / denom.sum()
xyz_z = z_numerator.sum() / denom.sum()
return XYZColor(xyz_x,
xyz_y,
xyz_z,
observer=cobj.observer,
illuminant=cobj.illuminant)
def set_illuminant(self, illuminant):
"""
Validates and sets the color's illuminant.
.. note:: This only changes the illuminant. It does no conversion
of the color's coordinates. For this, you'll want to refer to
:py:meth:`XYZColor.apply_adaptation <colormath.color_objects.XYZColor.apply_adaptation>`.
.. tip:: Call this after setting your observer.
:param str illuminant: One of the various illuminants.
"""
illuminant = illuminant.lower()
if illuminant not in color_constants.ILLUMINANTS[self.observer]:
raise InvalidIlluminantError(illuminant)
self.illuminant = illuminant