Source code for colour_hdri.models.dng

"""
Adobe DNG SDK Colour Processing
===============================

Defines various objects implementing *Adobe DNG SDK* colour processing:

-   :func:`colour_hdri.xy_to_camera_neutral`
-   :func:`colour_hdri.camera_neutral_to_xy`
-   :func:`colour_hdri.matrix_XYZ_to_camera_space`
-   :func:`colour_hdri.matrix_camera_space_to_XYZ`

The *Adobe DNG SDK* defines the following tags relevant for the current
implementation:

-   *CalibrationIlluminant1* : The illuminant used for the first set of colour
    calibration tags.
-   *CalibrationIlluminant2* : The illuminant used for an optional second set
    of colour calibration tags.
-   *ColorMatrix1* : *ColorMatrix1* defines a transformation matrix that
    converts XYZ values to reference camera native colour space values, under
    the first calibration illuminant.
-   *ColorMatrix2* : *ColorMatrix2* defines a transformation matrix that
    converts XYZ values to reference camera native colour space values, under
    the second calibration illuminant.
-   *CameraCalibration1* : *CameraCalibration1* defines a calibration matrix
    that transforms reference camera native space values to individual camera
    native space values under the first calibration illuminant. This matrix is
    stored separately from the matrix specified by the *ColorMatrix1* tag to
    allow raw converters to swap in replacement colour matrices based on
    *UniqueCameraModel* tag, while still taking advantage of any per-individual
    camera calibration performed by the camera manufacturer.
-   *CameraCalibration2* : *CameraCalibration2* defines a calibration matrix
    that transforms reference camera native space values to individual camera
    native space values under the second calibration illuminant. This matrix is
    stored separately from the matrix specified by the *ColorMatrix2* tag to
    allow raw converters to swap in replacement colour matrices based on
    *UniqueCameraModel* tag, while still taking advantage of any per-individual
    camera calibration performed by the camera manufacturer.
-   *ReductionMatrix1* : *ReductionMatrix1* defines a dimensionality reduction
    matrix for use as the first stage in converting colour camera native space
    values to XYZ values, under the first calibration illuminant. This tag may
    only be used if *ColorPlanes* is greater than 3.
-   *ReductionMatrix2* : *ReductionMatrix2* defines a dimensionality reduction
    matrix for use as the first stage in converting colour camera native space
    values to XYZ values, under the second calibration illuminant. This tag may
    only be used if *ColorPlanes* is greater than 3.
-   *AnalogBalance* : Normally the stored raw values are not white balanced,
    since any digital white balancing will reduce the dynamic range of the
    final image if the user decides to later adjust the white balance; however,
    if camera hardware is capable of white balancing the colour channels before
    the signal is digitized, it can improve the dynamic range of the final
    image. *AnalogBalance* defines the gain, either analog (recommended) or
    digital (not recommended) that has been applied the stored raw values.
-   *AsShotNeutral* : *AsShotNeutral* specifies the selected white balance at
    time of capture, encoded as the coordinates of a perfectly neutral colour
    in linear reference space values. The inclusion of this tag precludes the
    inclusion of the *AsShotWhiteXY* tag.
-   *AsShotWhiteXY* : *AsShotWhiteXY* specifies the selected white balance at
    time of capture, encoded as x-y chromaticity coordinates. The inclusion of
    this tag precludes the inclusion of the *AsShotNeutral* tag.
-   *ForwardMatrix1* : This tag defines a matrix that maps white balanced
    camera colours to XYZ D50 colours.
-   *ForwardMatrix2* : This tag defines a matrix that maps white balanced
    camera colours to XYZ D50 colours.

Notes
-----
-   At least one of the *ColorMatrix1* or *ColorMatrix2* tags must be included
    in the camera profile, the current implementation expects them to be passed
    as identity matrices if not included.
-   If the *ForwardMatrix1* or *ForwardMatrix2* tags are not included in the
    camera profile, the current implementation expects them to be passed as
    identity matrices.
-   The *ReductionMatrix1* and *ReductionMatrix2* tags are ignored by the
    current implementation which expects cameras with 3 colour planes.
-   *DNG 1.2.0.0* and later supports different companies creating the camera
    calibration tags using different reference cameras. When rendering a *DNG*
    file using a camera profile, it is important to know if the selected camera
    profile was designed using the same reference camera used to create the
    camera calibration tags. If so, then the camera calibration tags should be
    used. If not, then it is preferable to ignore the camera calibration tags
    and use identity matrices instead in order to minimize the worse case
    calibration mismatch error. This matching is done by comparing the
    *CameraCalibrationSignature* tag and the *ProfileCalibrationSignature* tag
    for the selected camera profile. If they match, then use the camera
    calibration tags. If not, then use identity matrices.
-   The Hue/Saturation/Value Mapping Table is ignored by the current
    implementation because deemed unsuitable :cite:`McGuffog2012a`.
-   The various matrices used in this module are extracted from a *Canon EOS 5D
    Mark II* camera.

References
----------
-   :cite:`AdobeSystems2012d` : Adobe Systems. (2012). Translating White
    Balance xy Coordinates to Camera Neutral Coordinates. In Digital Negative
    (DNG) Specification (p. 80).
-   :cite:`AdobeSystems2012e` : Adobe Systems. (2012). Translating Camera
    Neutral Coordinates to White Balance xy Coordinates. In Digital Negative
    (DNG) Specification (pp. 80-81).
-   :cite:`AdobeSystems2012f` : Adobe Systems. (2012). Digital Negative (DNG)
    Specification (pp. 1-101).
-   :cite:`AdobeSystems2012g` : Adobe Systems. (2012). Camera to XYZ (D50)
    Transform. In Digital Negative (DNG) Specification (p. 81).
-   :cite:`AdobeSystems2015d` : Adobe Systems. (2015). Adobe DNG SDK 1.4.
    http://download.adobe.com/pub/adobe/dng/dng_sdk_1_4.zip
-   :cite:`McGuffog2012a` : McGuffog, S. (2012). Hue Twists in DNG Camera
    Profiles. Retrieved October 29, 2016, from
    http://dcptool.sourceforge.net/Hue%20Twists.html
"""

from __future__ import annotations

import numpy as np
from colour.adaptation import matrix_chromatic_adaptation_VonKries
from colour.algebra import (
    is_identity,
    linear_conversion,
    matrix_dot,
    vector_dot,
)
from colour.constants import EPSILON
from colour.hints import ArrayLike, Literal, NDArrayFloat
from colour.models import UCS_to_uv, XYZ_to_UCS, XYZ_to_xy, xy_to_XYZ
from colour.temperature import uv_to_CCT_Robertson1968
from colour.utilities import as_float_array, tstack

from colour_hdri.models import CCS_ILLUMINANT_ADOBEDNG

__author__ = "Colour Developers"
__copyright__ = "Copyright 2015 Colour Developers"
__license__ = "BSD-3-Clause - https://opensource.org/licenses/BSD-3-Clause"
__maintainer__ = "Colour Developers"
__email__ = "colour-developers@colour-science.org"
__status__ = "Production"

__all__ = [
    "matrix_interpolated",
    "xy_to_camera_neutral",
    "camera_neutral_to_xy",
    "matrix_XYZ_to_camera_space",
    "matrix_camera_space_to_XYZ",
]


def matrix_interpolated(
    CCT: float,
    CCT_1: float,
    CCT_2: float,
    M_1: ArrayLike,
    M_2: ArrayLike,
) -> NDArrayFloat:
    """
    Compute the matrix interpolated from :math:`CCT_1` and :math:`CCT_2`
    correlated colour temperatures to respectively :math:`M_T` and :math:`M_R`
    colour matrices using given correlated colour temperature :math:`CCT`
    interpolation value.

    Parameters
    ----------
    CCT
        Correlated colour temperature :math:`CCT`.
    CCT_1
        Correlated colour temperature :math:`CCT_1`.
    CCT_2
        Correlated colour temperature :math:`CCT_2`.
    M_1
        :math:`M_T` colour matrix.
    M_2
        :math:`M_R` colour matrix.

    Returns
    -------
    :class:`numpy.ndarray`
        Interpolated colour matrix :math:`M_i`.

    Notes
    -----
    -   The computation is performed in mired (MIcro REciprocal Degree,
        reciprocal megakelvin) :math:`MK^{-1}`.

    Examples
    --------
    >>> CCT = 5000
    >>> CCT_1 = 2850
    >>> CCT_2 = 6500
    >>> M_T = np.array(
    ...     [
    ...         [0.5309, -0.0229, -0.0336],
    ...         [-0.6241, 1.3265, 0.3337],
    ...         [-0.0817, 0.1215, 0.6664],
    ...     ]
    ... )
    >>> M_R = np.array(
    ...     [
    ...         [0.4716, 0.0603, -0.0830],
    ...         [-0.7798, 1.5474, 0.2480],
    ...         [-0.1496, 0.1937, 0.6651],
    ...     ]
    ... )
    >>> matrix_interpolated(CCT, CCT_1, CCT_2, M_T, M_R)  # doctest: +ELLIPSIS
    array([[ 0.4854908...,  0.0408106..., -0.0714282...],
           [-0.7433278...,  1.4956549...,  0.2680749...],
           [-0.1336946...,  0.1767874...,  0.6654045...]])
    """

    M_1 = as_float_array(M_1)
    M_2 = as_float_array(M_2)

    if CCT <= CCT_1:
        return M_1
    elif CCT >= CCT_2:
        return M_2
    else:
        return linear_conversion(
            1e6 / CCT, (1e6 / CCT_1, 1e6 / CCT_2), tstack([M_1, M_2])
        )


[docs] def xy_to_camera_neutral( xy: ArrayLike, CCT_calibration_illuminant_1: float, CCT_calibration_illuminant_2: float, M_color_matrix_1: ArrayLike, M_color_matrix_2: ArrayLike, M_camera_calibration_1: ArrayLike, M_camera_calibration_2: ArrayLike, analog_balance: ArrayLike, ) -> NDArrayFloat: """ Convert given *xy* white balance chromaticity coordinates to *Camera Neutral* coordinates. Parameters ---------- xy *xy* white balance chromaticity coordinates. CCT_calibration_illuminant_1 Correlated colour temperature of *CalibrationIlluminant1*. CCT_calibration_illuminant_2 Correlated colour temperature of *CalibrationIlluminant2*. M_color_matrix_1 *ColorMatrix1* tag matrix. M_color_matrix_2 *ColorMatrix2* tag matrix. M_camera_calibration_1 *CameraCalibration1* tag matrix. M_camera_calibration_2 *CameraCalibration2* tag matrix. analog_balance *AnalogBalance* tag vector. Returns ------- :class:`numpy.ndarray` *Camera Neutral* coordinates. References ---------- :cite:`AdobeSystems2012d`, :cite:`AdobeSystems2012f`, :cite:`AdobeSystems2015d`, :cite:`McGuffog2012a` Examples -------- >>> M_color_matrix_1 = np.array( ... [ ... [0.5309, -0.0229, -0.0336], ... [-0.6241, 1.3265, 0.3337], ... [-0.0817, 0.1215, 0.6664], ... ] ... ) >>> M_color_matrix_2 = np.array( ... [ ... [0.4716, 0.0603, -0.0830], ... [-0.7798, 1.5474, 0.2480], ... [-0.1496, 0.1937, 0.6651], ... ] ... ) >>> M_camera_calibration_1 = np.identity(3) >>> M_camera_calibration_2 = np.identity(3) >>> analog_balance = np.ones(3) >>> xy_to_camera_neutral( # doctest: +ELLIPSIS ... np.array([0.32816244, 0.34698169]), ... 2850, ... 6500, ... M_color_matrix_1, ... M_color_matrix_2, ... M_camera_calibration_1, ... M_camera_calibration_2, ... analog_balance, ... ) array([ 0.4130699..., 1... , 0.646465...]) """ M_XYZ_to_camera = matrix_XYZ_to_camera_space( xy, CCT_calibration_illuminant_1, CCT_calibration_illuminant_2, M_color_matrix_1, M_color_matrix_2, M_camera_calibration_1, M_camera_calibration_2, analog_balance, ) camera_neutral = vector_dot(M_XYZ_to_camera, xy_to_XYZ(xy)) camera_neutral /= camera_neutral[1] return camera_neutral
[docs] def camera_neutral_to_xy( camera_neutral: ArrayLike, CCT_calibration_illuminant_1: float, CCT_calibration_illuminant_2: float, M_color_matrix_1: ArrayLike, M_color_matrix_2: ArrayLike, M_camera_calibration_1: ArrayLike, M_camera_calibration_2: ArrayLike, analog_balance: ArrayLike, epsilon: float = EPSILON, ) -> NDArrayFloat: """ Convert given *Camera Neutral* coordinates to *xy* white balance chromaticity coordinates. Parameters ---------- camera_neutral *Camera Neutral* coordinates. CCT_calibration_illuminant_1 Correlated colour temperature of *CalibrationIlluminant1*. CCT_calibration_illuminant_2 Correlated colour temperature of *CalibrationIlluminant2*. M_color_matrix_1 *ColorMatrix1* tag matrix. M_color_matrix_2 *ColorMatrix2* tag matrix. M_camera_calibration_1 *CameraCalibration1* tag matrix. M_camera_calibration_2 *CameraCalibration2* tag matrix. analog_balance *AnalogBalance* tag vector. epsilon Threshold value for computation convergence. Returns ------- :class:`numpy.ndarray` *xy* white balance chromaticity coordinates. Raises ------ RuntimeError If the given *Camera Neutral* coordinates did not converge to *xy* white balance chromaticity coordinates. References ---------- :cite:`AdobeSystems2012e`, :cite:`AdobeSystems2012f`, :cite:`AdobeSystems2015d`, :cite:`McGuffog2012a` Examples -------- >>> M_color_matrix_1 = np.array( ... [ ... [0.5309, -0.0229, -0.0336], ... [-0.6241, 1.3265, 0.3337], ... [-0.0817, 0.1215, 0.6664], ... ] ... ) >>> M_color_matrix_2 = np.array( ... [ ... [0.4716, 0.0603, -0.0830], ... [-0.7798, 1.5474, 0.2480], ... [-0.1496, 0.1937, 0.6651], ... ] ... ) >>> M_camera_calibration_1 = np.identity(3) >>> M_camera_calibration_2 = np.identity(3) >>> analog_balance = np.ones(3) >>> camera_neutral_to_xy( # doctest: +ELLIPSIS ... np.array([0.413070, 1.000000, 0.646465]), ... 2850, ... 6500, ... M_color_matrix_1, ... M_color_matrix_2, ... M_camera_calibration_1, ... M_camera_calibration_2, ... analog_balance, ... ) array([ 0.3281624..., 0.3469816...]) """ # Initial *xy* chromaticity coordinates guess. xy = np.array((1 / 3, 1 / 3)) while True: xy_p = np.copy(xy) M_XYZ_to_camera = matrix_XYZ_to_camera_space( xy, CCT_calibration_illuminant_1, CCT_calibration_illuminant_2, M_color_matrix_1, M_color_matrix_2, M_camera_calibration_1, M_camera_calibration_2, analog_balance, ) XYZ = vector_dot(np.linalg.inv(M_XYZ_to_camera), camera_neutral) xy = XYZ_to_xy(XYZ) if np.abs(np.sum(xy_p - xy)) <= epsilon: return xy raise RuntimeError( f'"Camera Neutral" coordinates "{xy}" did not converge to "xy" white ' f"balance chromaticity coordinates!" )
[docs] def matrix_XYZ_to_camera_space( xy: ArrayLike, CCT_calibration_illuminant_1: float, CCT_calibration_illuminant_2: float, M_color_matrix_1: ArrayLike, M_color_matrix_2: ArrayLike, M_camera_calibration_1: ArrayLike, M_camera_calibration_2: ArrayLike, analog_balance: ArrayLike, ) -> NDArrayFloat: """ Return the *CIE XYZ* to *Camera Space* matrix for given *xy* white balance chromaticity coordinates. Parameters ---------- xy *xy* white balance chromaticity coordinates. CCT_calibration_illuminant_1 Correlated colour temperature of *CalibrationIlluminant1*. CCT_calibration_illuminant_2 Correlated colour temperature of *CalibrationIlluminant2*. M_color_matrix_1 *ColorMatrix1* tag matrix. M_color_matrix_2 *ColorMatrix2* tag matrix. M_camera_calibration_1 *CameraCalibration1* tag matrix. M_camera_calibration_2 *CameraCalibration2* tag matrix. analog_balance *AnalogBalance* tag vector. Returns ------- :class:`numpy.ndarray` *CIE XYZ* to *Camera Space* matrix. Notes ----- - The reference illuminant is D50 as defined per :attr:`colour_hdri.models.datasets.dng.CCS_ILLUMINANT_ADOBEDNG` attribute. References ---------- :cite:`AdobeSystems2012f`, :cite:`AdobeSystems2015d`, :cite:`McGuffog2012a` Examples -------- >>> M_color_matrix_1 = np.array( ... [ ... [0.5309, -0.0229, -0.0336], ... [-0.6241, 1.3265, 0.3337], ... [-0.0817, 0.1215, 0.6664], ... ] ... ) >>> M_color_matrix_2 = np.array( ... [ ... [0.4716, 0.0603, -0.0830], ... [-0.7798, 1.5474, 0.2480], ... [-0.1496, 0.1937, 0.6651], ... ] ... ) >>> M_camera_calibration_1 = np.identity(3) >>> M_camera_calibration_2 = np.identity(3) >>> analog_balance = np.ones(3) >>> matrix_XYZ_to_camera_space( # doctest: +ELLIPSIS ... np.array([0.34510414, 0.35162252]), ... 2850, ... 6500, ... M_color_matrix_1, ... M_color_matrix_2, ... M_camera_calibration_1, ... M_camera_calibration_2, ... analog_balance, ... ) array([[ 0.4854908..., 0.0408106..., -0.0714282...], [-0.7433278..., 1.4956549..., 0.2680749...], [-0.1336946..., 0.1767874..., 0.6654045...]]) """ M_AB = np.diagflat(analog_balance) uv = UCS_to_uv(XYZ_to_UCS(xy_to_XYZ(xy))) CCT, _D_uv = uv_to_CCT_Robertson1968(uv) if is_identity(M_color_matrix_1) or is_identity(M_color_matrix_2): M_CM = M_color_matrix_1 if is_identity(M_color_matrix_2) else M_color_matrix_2 else: M_CM = matrix_interpolated( CCT, CCT_calibration_illuminant_1, CCT_calibration_illuminant_2, M_color_matrix_1, M_color_matrix_2, ) M_CC = matrix_interpolated( CCT, CCT_calibration_illuminant_1, CCT_calibration_illuminant_2, M_camera_calibration_1, M_camera_calibration_2, ) M_XYZ_to_camera_space = matrix_dot(matrix_dot(M_AB, M_CC), M_CM) return M_XYZ_to_camera_space
[docs] def matrix_camera_space_to_XYZ( xy: ArrayLike, CCT_calibration_illuminant_1: float, CCT_calibration_illuminant_2: float, M_color_matrix_1: ArrayLike, M_color_matrix_2: ArrayLike, M_camera_calibration_1: ArrayLike, M_camera_calibration_2: ArrayLike, analog_balance: ArrayLike, M_forward_matrix_1: ArrayLike, M_forward_matrix_2: ArrayLike, chromatic_adaptation_transform: ( Literal[ "Bianco 2010", "Bianco PC 2010", "Bradford", "CAT02 Brill 2008", "CAT02", "CAT16", "CMCCAT2000", "CMCCAT97", "Fairchild", "Sharp", "Von Kries", "XYZ Scaling", ] | str ) = "Bradford", ) -> NDArrayFloat: """ Return the *Camera Space* to *CIE XYZ* matrix for given *xy* white balance chromaticity coordinates. Parameters ---------- xy *xy* white balance chromaticity coordinates. CCT_calibration_illuminant_1 Correlated colour temperature of *CalibrationIlluminant1*. CCT_calibration_illuminant_2 Correlated colour temperature of *CalibrationIlluminant2*. M_color_matrix_1 *ColorMatrix1* tag matrix. M_color_matrix_2 *ColorMatrix2* tag matrix. M_camera_calibration_1 *CameraCalibration1* tag matrix. M_camera_calibration_2 *CameraCalibration2* tag matrix. analog_balance *AnalogBalance* tag vector. M_forward_matrix_1 *ForwardMatrix1* tag matrix. M_forward_matrix_2 *ForwardMatrix2* tag matrix. chromatic_adaptation_transform Chromatic adaptation transform. Returns ------- :class:`numpy.ndarray` *Camera Space* to *CIE XYZ* matrix. Notes ----- - The reference illuminant is D50 as defined per :attr:`colour_hdri.models.datasets.dng.CCS_ILLUMINANT_ADOBEDNG` attribute. References ---------- :cite:`AdobeSystems2012f`, :cite:`AdobeSystems2012g`, :cite:`AdobeSystems2015d`, :cite:`McGuffog2012a` Examples -------- >>> M_color_matrix_1 = np.array( ... [ ... [0.5309, -0.0229, -0.0336], ... [-0.6241, 1.3265, 0.3337], ... [-0.0817, 0.1215, 0.6664], ... ] ... ) >>> M_color_matrix_2 = np.array( ... [ ... [0.4716, 0.0603, -0.0830], ... [-0.7798, 1.5474, 0.2480], ... [-0.1496, 0.1937, 0.6651], ... ] ... ) >>> M_camera_calibration_1 = np.identity(3) >>> M_camera_calibration_2 = np.identity(3) >>> analog_balance = np.ones(3) >>> M_forward_matrix_1 = np.array( ... [ ... [0.8924, -0.1041, 0.1760], ... [0.4351, 0.6621, -0.0972], ... [0.0505, -0.1562, 0.9308], ... ] ... ) >>> M_forward_matrix_2 = np.array( ... [ ... [0.8924, -0.1041, 0.1760], ... [0.4351, 0.6621, -0.0972], ... [0.0505, -0.1562, 0.9308], ... ] ... ) >>> matrix_camera_space_to_XYZ( # doctest: +ELLIPSIS ... np.array([0.32816244, 0.34698169]), ... 2850, ... 6500, ... M_color_matrix_1, ... M_color_matrix_2, ... M_camera_calibration_1, ... M_camera_calibration_2, ... analog_balance, ... M_forward_matrix_1, ... M_forward_matrix_2, ... ) array([[ 2.1604087..., -0.1041... , 0.2722498...], [ 1.0533324..., 0.6621... , -0.1503561...], [ 0.1222553..., -0.1562... , 1.4398304...]]) """ # *ForwardMatrix1* and *ForwardMatrix2* are not included in the camera # profile. if is_identity(M_forward_matrix_1) and is_identity(M_forward_matrix_2): M_camera_to_XYZ = np.linalg.inv( matrix_XYZ_to_camera_space( xy, CCT_calibration_illuminant_1, CCT_calibration_illuminant_2, M_color_matrix_1, M_color_matrix_2, M_camera_calibration_1, M_camera_calibration_2, analog_balance, ) ) M_CAT = matrix_chromatic_adaptation_VonKries( xy_to_XYZ(xy), xy_to_XYZ(CCS_ILLUMINANT_ADOBEDNG), chromatic_adaptation_transform, ) M_camera_space_to_XYZ = matrix_dot(M_CAT, M_camera_to_XYZ) else: uv = UCS_to_uv(XYZ_to_UCS(xy_to_XYZ(xy))) CCT, _D_uv = uv_to_CCT_Robertson1968(uv) M_CC = matrix_interpolated( CCT, CCT_calibration_illuminant_1, CCT_calibration_illuminant_2, M_camera_calibration_1, M_camera_calibration_2, ) # The reference implementation :cite:`AdobeSystems2015d` diverges from # the white-paper :cite:`AdobeSystems2012f`: # The reference implementation directly computes the camera neutral by # multiplying directly the interpolated colour matrix :math:`CM` with # the tristimulus values of the *xy* white balance chromaticity # coordinates. # The current implementation is based on the white-paper so that the # interpolated camera calibration matrix :math:`CC` and the # analog balance matrix :math:`AB` are accounted for. camera_neutral = xy_to_camera_neutral( xy, CCT_calibration_illuminant_1, CCT_calibration_illuminant_2, M_color_matrix_1, M_color_matrix_2, M_camera_calibration_1, M_camera_calibration_2, analog_balance, ) M_AB = np.diagflat(analog_balance) M_reference_neutral = vector_dot( np.linalg.inv(matrix_dot(M_AB, M_CC)), camera_neutral ) M_D = np.linalg.inv(np.diagflat(M_reference_neutral)) M_FM = matrix_interpolated( CCT, CCT_calibration_illuminant_1, CCT_calibration_illuminant_2, M_forward_matrix_1, M_forward_matrix_2, ) M_camera_space_to_XYZ = matrix_dot( matrix_dot(M_FM, M_D), np.linalg.inv(matrix_dot(M_AB, M_CC)) ) return M_camera_space_to_XYZ