Source code for colour.models.cie_uvw

"""
CIE 1964 U*V*W* Colourspace
===========================

Defines the *CIE 1964 U\\*V\\*W\\** colourspace transformations:

-   :func:`colour.XYZ_to_UVW`
-   :func:`colour.UVW_to_XYZ`

References
----------
-   :cite:`Wikipedia2008a` : Wikipedia. (2008). CIE 1964 color space.
    Retrieved June 10, 2014, from
    http://en.wikipedia.org/wiki/CIE_1964_color_space
"""

from __future__ import annotations

import numpy as np

from colour.algebra import sdiv, sdiv_mode, spow
from colour.colorimetry import CCS_ILLUMINANTS
from colour.hints import ArrayLike, NDArray, cast
from colour.models import (
    UCS_uv_to_xy,
    XYZ_to_xy,
    xy_to_UCS_uv,
    xyY_to_XYZ,
    xyY_to_xy,
)
from colour.utilities import from_range_100, to_domain_100, tsplit, tstack

__author__ = "Colour Developers"
__copyright__ = "Copyright 2013 Colour Developers"
__license__ = "New BSD License - https://opensource.org/licenses/BSD-3-Clause"
__maintainer__ = "Colour Developers"
__email__ = "colour-developers@colour-science.org"
__status__ = "Production"

__all__ = [
    "XYZ_to_UVW",
    "UVW_to_XYZ",
]


[docs]def XYZ_to_UVW( XYZ: ArrayLike, illuminant: ArrayLike = CCS_ILLUMINANTS[ "CIE 1931 2 Degree Standard Observer" ]["D65"], ) -> NDArray: """ Convert from *CIE XYZ* tristimulus values to *CIE 1964 U\\*V\\*W\\** colourspace. Parameters ---------- XYZ *CIE XYZ* tristimulus values. illuminant Reference *illuminant* *CIE xy* chromaticity coordinates or *CIE xyY* colourspace array. Returns ------- :class:`numpy.ndarray` *CIE 1964 U\\*V\\*W\\** colourspace array. Notes ----- +----------------+-----------------------+-----------------+ | **Domain** | **Scale - Reference** | **Scale - 1** | +================+=======================+=================+ | ``XYZ`` | [0, 100] | [0, 1] | +----------------+-----------------------+-----------------+ | ``illuminant`` | [0, 1] | [0, 1] | +----------------+-----------------------+-----------------+ +----------------+-----------------------+-----------------+ | **Range** | **Scale - Reference** | **Scale - 1** | +================+=======================+=================+ | ``UVW`` | ``U`` : [-100, 100] | ``U`` : [-1, 1] | | | | | | | ``V`` : [-100, 100] | ``V`` : [-1, 1] | | | | | | | ``W`` : [0, 100] | ``W`` : [0, 1] | +----------------+-----------------------+-----------------+ References ---------- :cite:`Wikipedia2008a` Examples -------- >>> import numpy as np >>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952]) * 100 >>> XYZ_to_UVW(XYZ) # doctest: +ELLIPSIS array([ 94.5503572..., 11.5553652..., 40.5475740...]) """ XYZ = to_domain_100(XYZ) xy = XYZ_to_xy(XYZ / 100) xy_n = xyY_to_xy(illuminant) Y = XYZ[..., 1] uv = xy_to_UCS_uv(xy) uv_0 = xy_to_UCS_uv(xy_n) W = 25 * cast(NDArray, spow(Y, 1 / 3)) - 17 U, V = tsplit(13 * W[..., np.newaxis] * (uv - uv_0)) UVW = tstack([U, V, W]) return from_range_100(UVW)
[docs]def UVW_to_XYZ( UVW: ArrayLike, illuminant: ArrayLike = CCS_ILLUMINANTS[ "CIE 1931 2 Degree Standard Observer" ]["D65"], ) -> NDArray: """ Convert *CIE 1964 U\\*V\\*W\\** colourspace to *CIE XYZ* tristimulus values. Parameters ---------- UVW *CIE 1964 U\\*V\\*W\\** colourspace array. illuminant Reference *illuminant* *CIE xy* chromaticity coordinates or *CIE xyY* colourspace array. Returns ------- :class:`numpy.ndarray` *CIE XYZ* tristimulus values. Notes ----- +----------------+-----------------------+-----------------+ | **Domain** | **Scale - Reference** | **Scale - 1** | +================+=======================+=================+ | ``UVW`` | ``U`` : [-100, 100] | ``U`` : [-1, 1] | | | | | | | ``V`` : [-100, 100] | ``V`` : [-1, 1] | | | | | | | ``W`` : [0, 100] | ``W`` : [0, 1] | +----------------+-----------------------+-----------------+ | ``illuminant`` | [0, 1] | [0, 1] | +----------------+-----------------------+-----------------+ +----------------+-----------------------+-----------------+ | **Range** | **Scale - Reference** | **Scale - 1** | +================+=======================+=================+ | ``XYZ`` | [0, 100 | [0, 1] | +----------------+-----------------------+-----------------+ References ---------- :cite:`Wikipedia2008a` Examples -------- >>> import numpy as np >>> UVW = np.array([94.55035725, 11.55536523, 40.54757405]) >>> UVW_to_XYZ(UVW) array([ 20.654008, 12.197225, 5.136952]) """ U, V, W = tsplit(to_domain_100(UVW)) u_0, v_0 = tsplit(xy_to_UCS_uv(xyY_to_xy(illuminant))) Y = ((W + 17) / 25) ** 3 with sdiv_mode(): u = sdiv(U, 13 * W) + u_0 v = sdiv(V, 13 * W) + v_0 x, y = tsplit(UCS_uv_to_xy(tstack([u, v]))) XYZ = xyY_to_XYZ(tstack([x, y, Y])) return from_range_100(XYZ)