Python colorimetry.ILLUMINANTS类代码示例

def RGB_to_Lab(RGB, colourspace):
    """
    Converts given *RGB* value from given colourspace to *CIE Lab* colourspace.

    Parameters
    ----------
    RGB : array_like
        *RGB* value.
    colourspace : RGB_Colourspace
        *RGB* colourspace.

    Returns
    -------
    bool
        Definition success.
    """

    return XYZ_to_Lab(
        RGB_to_XYZ(np.array(RGB),
                   colourspace.whitepoint,
                   ILLUMINANTS.get(
                       'CIE 1931 2 Degree Standard Observer').get('E'),
                   colourspace.to_XYZ,
                   'Bradford',
                   colourspace.decoding_cctf),
        colourspace.whitepoint)

def XYZ_to_xy(XYZ, illuminant=ILLUMINANTS.get("CIE 1931 2 Degree Standard Observer").get("D50")):
    """
    Returns the *xy* chromaticity coordinates from given *CIE XYZ* tristimulus
    values.

    Parameters
    ----------
    XYZ : array_like
        *CIE XYZ* tristimulus values.
    illuminant : array_like, optional
        Reference *illuminant* chromaticity coordinates.

    Returns
    -------
    ndarray
        *xy* chromaticity coordinates.

    Notes
    -----
    -   Input *CIE XYZ* tristimulus values are in domain [0, 1].
    -   Output *xy* chromaticity coordinates are in domain [0, 1].

    Examples
    --------
    >>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313])
    >>> XYZ_to_xy(XYZ)  # doctest: +ELLIPSIS
    array([ 0.2641477...,  0.3777000...])
    """

    xy = xyY_to_xy(XYZ_to_xyY(XYZ, illuminant))

    return xy

def XYZ_to_xy(XYZ,
              illuminant=ILLUMINANTS.get(
                  'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Returns the *xy* chromaticity coordinates from given *CIE XYZ* colourspace
    matrix.

    Parameters
    ----------
    XYZ : array_like, (3,)
        *CIE XYZ* colourspace matrix.
    illuminant : array_like, optional
        Reference *illuminant* chromaticity coordinates.

    Returns
    -------
    tuple
        *xy* chromaticity coordinates.

    Notes
    -----
    -   Input *CIE XYZ* colourspace matrix is in domain [0, 1].
    -   Output *xy* chromaticity coordinates are in domain [0, 1].

    Examples
    --------
    >>> XYZ_to_xy(np.array([0.97137399, 1, 1.04462134]))  # doctest: +ELLIPSIS
    (0.3220741..., 0.3315655...)
    >>> XYZ_to_xy((0.97137399, 1, 1.04462134))  # doctest: +ELLIPSIS
    (0.3220741..., 0.3315655...)
    """

    xyY = np.ravel(XYZ_to_xyY(XYZ, illuminant))
    return xyY[0], xyY[1]

def XYZ_to_xy(XYZ,
              illuminant=ILLUMINANTS.get(
                  'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Returns the *xy* chromaticity coordinates from given *CIE XYZ* colourspace
    matrix.

    Parameters
    ----------
    XYZ : array_like, (3,)
        *CIE XYZ* colourspace matrix.
    illuminant : array_like, optional
        Reference *illuminant* chromaticity coordinates.

    Returns
    -------
    tuple
        *xy* chromaticity coordinates.

    Notes
    -----
    -   Input *CIE XYZ* colourspace matrix is in domain [0, 1].
    -   Output *xy* chromaticity coordinates are in domain [0, 1].

    Examples
    --------
    >>> XYZ = np.array([0.07049534, 0.1008, 0.09558313])
    >>> XYZ_to_xy(XYZ)  # doctest: +ELLIPSIS
    (0.2641477..., 0.3777000...)
    """

    xyY = np.ravel(XYZ_to_xyY(XYZ, illuminant))
    return xyY[0], xyY[1]

def Luv_to_XYZ(Luv,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE Luv* colourspace to *CIE XYZ* tristimulus values.

    Parameters
    ----------
    Luv : array_like
        *CIE Luv* colourspace array.
    illuminant : array_like, optional
        Reference *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array.

    Returns
    -------
    ndarray
        *CIE XYZ* tristimulus values.

    Notes
    -----
    -   Input :math:`L^*` is in domain [0, 100].
    -   Input *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array are in domain [0, :math:`\infty`].
    -   Output *CIE XYZ* tristimulus values are in range [0, 1].

    References
    ----------
    .. [3]  Lindbloom, B. (2003). Luv to XYZ. Retrieved February 24, 2014,
            from http://brucelindbloom.com/Eqn_Luv_to_XYZ.html

    Examples
    --------
    >>> Luv = np.array([37.9856291 , -28.80219593,  -1.35800706])
    >>> Luv_to_XYZ(Luv)  # doctest: +ELLIPSIS
    array([ 0.0704953...,  0.1008    ,  0.0955831...])
    """

    L, u, v = tsplit(Luv)
    X_r, Y_r, Z_r = tsplit(xyY_to_XYZ(xy_to_xyY(illuminant)))

    Y = np.where(L > CIE_E * CIE_K, ((L + 16) / 116) ** 3, L / CIE_K)

    a = 1 / 3 * ((52 * L / (u + 13 * L *
                            (4 * X_r / (X_r + 15 * Y_r + 3 * Z_r)))) - 1)
    b = -5 * Y
    c = -1 / 3.0
    d = Y * (39 * L / (v + 13 * L *
                       (9 * Y_r / (X_r + 15 * Y_r + 3 * Z_r))) - 5)

    X = (d - b) / (a - c)
    Z = X * a + b

    XYZ = tstack((X, Y, Z))

    return XYZ

def XYZ_to_Lab(XYZ,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE XYZ* tristimulus values to *CIE Lab* colourspace.

    Parameters
    ----------
    XYZ : array_like
        *CIE XYZ* tristimulus values.
    illuminant : array_like, optional
        Reference *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array.

    Returns
    -------
    ndarray
        *CIE Lab* colourspace array.

    Notes
    -----
    -   Input *CIE XYZ* tristimulus values are in domain [0, 1].
    -   Input *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array are in domain [0, :math:`\infty`].
    -   Output *Lightness* :math:`L^*` is in domain [0, 100].

    References
    ----------
    .. [2]  Lindbloom, B. (2003). XYZ to Lab. Retrieved February 24, 2014,
            from http://www.brucelindbloom.com/Eqn_XYZ_to_Lab.html

    Examples
    --------
    >>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313])
    >>> XYZ_to_Lab(XYZ)  # doctest: +ELLIPSIS
    array([ 37.9856291..., -23.6230288...,  -4.4141703...])
    """

    XYZ = np.asarray(XYZ)
    XYZ_r = xyY_to_XYZ(xy_to_xyY(illuminant))

    XYZ_f = XYZ / XYZ_r

    XYZ_f = np.where(XYZ_f > CIE_E,
                     np.power(XYZ_f, 1 / 3),
                     (CIE_K * XYZ_f + 16) / 116)

    X_f, Y_f, Z_f = tsplit(XYZ_f)

    L = 116 * Y_f - 16
    a = 500 * (X_f - Y_f)
    b = 200 * (Y_f - Z_f)

    Lab = tstack((L, a, b))

    return Lab

def XYZ_to_Luv(XYZ,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE XYZ* tristimulus values to *CIE Luv* colourspace.

    Parameters
    ----------
    XYZ : array_like
        *CIE XYZ* tristimulus values.
    illuminant : array_like, optional
        Reference *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array.

    Returns
    -------
    ndarray
        *CIE Luv* colourspace array.

    Notes
    -----
    -   Input *CIE XYZ* tristimulus values are in domain [0, 1].
    -   Input *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array are in domain [0, :math:`\infty`].
    -   Output :math:`L^*` is in range [0, 100].

    References
    ----------
    .. [2]  Lindbloom, B. (2003). XYZ to Luv. Retrieved February 24, 2014,
            from http://brucelindbloom.com/Eqn_XYZ_to_Luv.html

    Examples
    --------
    >>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313])
    >>> XYZ_to_Luv(XYZ)  # doctest: +ELLIPSIS
    array([ 37.9856291..., -28.8021959...,  -1.3580070...])
    """

    X, Y, Z = tsplit(XYZ)
    X_r, Y_r, Z_r = tsplit(xyY_to_XYZ(xy_to_xyY(illuminant)))

    y_r = Y / Y_r

    L = np.where(y_r > CIE_E, 116 * y_r ** (1 / 3) - 16, CIE_K * y_r)

    u = (13 * L * ((4 * X / (X + 15 * Y + 3 * Z)) -
                   (4 * X_r / (X_r + 15 * Y_r + 3 * Z_r))))
    v = (13 * L * ((9 * Y / (X + 15 * Y + 3 * Z)) -
                   (9 * Y_r / (X_r + 15 * Y_r + 3 * Z_r))))

    Luv = tstack((L, u, v))

    return Luv

def XYZ_to_UVW(XYZ,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE XYZ* tristimulus values to *CIE 1964 U\*V\*W\**
    colourspace.

    Parameters
    ----------
    XYZ : array_like
        *CIE XYZ* tristimulus values.
    illuminant : array_like, optional
        Reference *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array.

    Returns
    -------
    ndarray
        *CIE 1964 U\*V\*W\** colourspace array.

    Notes
    -----
    -   Input *CIE XYZ* tristimulus values are in domain [0, 100].
    -   Input *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array are in domain [0, :math:`\infty`].
    -   Output *CIE UVW* colourspace array is in range [0, 100].

    Warning
    -------
    The input / output domains of that definition are non standard!

    Examples
    --------
    >>> import numpy as np
    >>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313]) * 100
    >>> XYZ_to_UVW(XYZ)  # doctest: +ELLIPSIS
    array([-28.0579733...,  -0.8819449...,  37.0041149...])
    """

    xyY = XYZ_to_xyY(XYZ, xyY_to_xy(illuminant))
    _x, _y, Y = tsplit(xyY)

    u, v = tsplit(UCS_to_uv(XYZ_to_UCS(XYZ)))
    u_0, v_0 = tsplit(
        UCS_to_uv(XYZ_to_UCS(xyY_to_XYZ(xy_to_xyY(illuminant)))))

    W = 25 * Y ** (1 / 3) - 17
    U = 13 * W * (u - u_0)
    V = 13 * W * (v - v_0)

    UVW = tstack((U, V, W))

    return UVW

def Lab_to_XYZ(Lab,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE Lab* colourspace to *CIE XYZ* colourspace.

    Parameters
    ----------
    Lab : array_like, (3,)
        *CIE Lab* colourspace matrix.
    illuminant : array_like, optional
        Reference *illuminant* chromaticity coordinates.

    Returns
    -------
    ndarray, (3,)
        *CIE XYZ* colourspace matrix.

    Notes
    -----
    -   Input *Lightness* :math:`L^*` is in domain [0, 100].
    -   Input *illuminant* chromaticity coordinates are in domain [0, 1].
    -   Output *CIE XYZ* colourspace matrix is in domain [0, 1].

    References
    ----------
    .. [3]  http://www.brucelindbloom.com/Eqn_Lab_to_XYZ.html
            (Last accessed 24 February 2014)

    Examples
    --------
    >>> Lab = np.array([100, -7.41787844, -15.85742105])
    >>> Lab_to_XYZ(Lab)  # doctest: +ELLIPSIS
    array([ 0.9219310...,  1.        ,  1.0374424...])
    """

    L, a, b = np.ravel(Lab)
    Xr, Yr, Zr = np.ravel(xy_to_XYZ(illuminant))

    fy = (L + 16) / 116
    fx = a / 500 + fy
    fz = fy - b / 200

    xr = fx ** 3 if fx ** 3 > CIE_E else (116 * fx - 16) / CIE_K
    yr = ((L + 16) / 116) ** 3 if L > CIE_K * CIE_E else L / CIE_K
    zr = fz ** 3 if fz ** 3 > CIE_E else (116 * fz - 16) / CIE_K

    X = xr * Xr
    Y = yr * Yr
    Z = zr * Zr

    return np.array([X, Y, Z])

def Luv_to_XYZ(Luv,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE Luv* colourspace to *CIE XYZ* colourspace.

    Parameters
    ----------
    Luv : array_like, (3,)
        *CIE Luv* colourspace matrix.
    illuminant : array_like, optional
        Reference *illuminant* chromaticity coordinates.

    Returns
    -------
    ndarray, (3,)
        *CIE XYZ* colourspace matrix.

    Notes
    -----
    -   Input :math:`L^*` is in domain [0, 100].
    -   Input *illuminant* chromaticity coordinates are in domain [0, 1].
    -   Output *CIE XYZ* colourspace matrix is in domain [0, 1].

    References
    ----------
    .. [3]  http://brucelindbloom.com/Eqn_Luv_to_XYZ.html
            (Last accessed 24 February 2014)

    Examples
    --------
    >>> Luv = np.array([100, -20.04304247, -19.81676035])
    >>> Luv_to_XYZ(Luv)  # doctest: +ELLIPSIS
    array([ 0.9219310...,  1.        ,  1.0374424...])
    """

    L, u, v = np.ravel(Luv)
    Xr, Yr, Zr = np.ravel(xy_to_XYZ(illuminant))

    Y = ((L + 16) / 116) ** 3 if L > CIE_E * CIE_K else L / CIE_K

    a = 1 / 3 * ((52 * L / (u + 13 * L *
                            (4 * Xr / (Xr + 15 * Yr + 3 * Zr)))) - 1)
    b = -5 * Y
    c = -1 / 3.0
    d = Y * (39 * L / (v + 13 * L *
                       (9 * Yr / (Xr + 15 * Yr + 3 * Zr))) - 5)

    X = (d - b) / (a - c)
    Z = X * a + b

    return np.array([X, Y, Z])

def Lab_to_XYZ(Lab,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE Lab* colourspace to *CIE XYZ* tristimulus values.

    Parameters
    ----------
    Lab : array_like
        *CIE Lab* colourspace array.
    illuminant : array_like, optional
        Reference *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array.

    Returns
    -------
    ndarray
        *CIE XYZ* tristimulus values.

    Notes
    -----
    -   Input *Lightness* :math:`L^*` is in domain [0, 100].
    -   Input *illuminant* *xy* chromaticity coordinates or *CIE xyY*
        colourspace array are in domain [0, :math:`\infty`].
    -   Output *CIE XYZ* tristimulus values are in domain [0, 1].

    References
    ----------
    .. [3]  Lindbloom, B. (2008). Lab to XYZ. Retrieved February 24, 2014,
            from http://www.brucelindbloom.com/Eqn_Lab_to_XYZ.html

    Examples
    --------
    >>> Lab = np.array([37.98562910, -23.62302887, -4.41417036])
    >>> Lab_to_XYZ(Lab)  # doctest: +ELLIPSIS
    array([ 0.0704953...,  0.1008    ,  0.0955831...])
    """

    L, a, b = tsplit(Lab)
    XYZ_r = xyY_to_XYZ(xy_to_xyY(illuminant))

    f_y = (L + 16) / 116
    f_x = a / 500 + f_y
    f_z = f_y - b / 200

    x_r = np.where(f_x ** 3 > CIE_E, f_x ** 3, (116 * f_x - 16) / CIE_K)
    y_r = np.where(L > CIE_K * CIE_E, ((L + 16) / 116) ** 3, L / CIE_K)
    z_r = np.where(f_z ** 3 > CIE_E, f_z ** 3, (116 * f_z - 16) / CIE_K)

    XYZ = tstack((x_r, y_r, z_r)) * XYZ_r

    return XYZ

def Luv_to_XYZ(Luv,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE Luv* colourspace to *CIE XYZ* colourspace.

    Parameters
    ----------
    Luv : array_like, (3,)
        *CIE Luv* colourspace matrix.
    illuminant : array_like, optional
        Reference *illuminant* chromaticity coordinates.

    Returns
    -------
    ndarray, (3,)
        *CIE XYZ* colourspace matrix.

    Notes
    -----
    -   Input :math:`L^*` is in domain [0, 100].
    -   Input *illuminant* chromaticity coordinates are in domain [0, 1].
    -   Output *CIE XYZ* colourspace matrix is in domain [0, 1].

    References
    ----------
    .. [3]  Lindbloom, B. (2003). Luv to XYZ. Retrieved February 24, 2014,
            from http://brucelindbloom.com/Eqn_Luv_to_XYZ.html

    Examples
    --------
    >>> Luv = np.array([37.9856291, -28.79229446, -1.3558195])
    >>> Luv_to_XYZ(Luv)  # doctest: +ELLIPSIS
    array([ 0.0704953...,  0.1008    ,  0.0955831...])
    """

    L, u, v = np.ravel(Luv)
    Xr, Yr, Zr = np.ravel(xy_to_XYZ(illuminant))

    Y = ((L + 16) / 116) ** 3 if L > CIE_E * CIE_K else L / CIE_K

    a = 1 / 3 * ((52 * L / (u + 13 * L *
                            (4 * Xr / (Xr + 15 * Yr + 3 * Zr)))) - 1)
    b = -5 * Y
    c = -1 / 3.0
    d = Y * (39 * L / (v + 13 * L *
                       (9 * Yr / (Xr + 15 * Yr + 3 * Zr))) - 5)

    X = (d - b) / (a - c)
    Z = X * a + b

    return np.array([X, Y, Z])

def XYZ_to_Lab(XYZ,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE XYZ* colourspace to *CIE Lab* colourspace.

    Parameters
    ----------
    XYZ : array_like, (3,)
        *CIE XYZ* colourspace matrix.
    illuminant : array_like, optional
        Reference *illuminant* chromaticity coordinates.

    Returns
    -------
    ndarray, (3,)
        *CIE Lab* colourspace matrix.

    Notes
    -----
    -   Input *CIE XYZ* is in domain [0, 1].
    -   Input *illuminant* chromaticity coordinates are in domain [0, 1].
    -   Output *Lightness* :math:`L^*` is in domain [0, 100].

    References
    ----------
    .. [2]  http://www.brucelindbloom.com/Eqn_XYZ_to_Lab.html
            (Last accessed 24 February 2014)

    Examples
    --------
    >>> XYZ_to_Lab(np.array([0.92193107, 1, 1.03744246]))  # doctest: +ELLIPSIS
    array([ 100.        ,   -7.4178784...,  -15.8574210...])
    """

    X, Y, Z = np.ravel(XYZ)
    Xr, Yr, Zr = np.ravel(xy_to_XYZ(illuminant))

    xr = X / Xr
    yr = Y / Yr
    zr = Z / Zr

    fx = xr ** (1 / 3) if xr > CIE_E else (CIE_K * xr + 16) / 116
    fy = yr ** (1 / 3) if yr > CIE_E else (CIE_K * yr + 16) / 116
    fz = zr ** (1 / 3) if zr > CIE_E else (CIE_K * zr + 16) / 116

    L = 116 * fy - 16
    a = 500 * (fx - fy)
    b = 200 * (fy - fz)

    return np.array([L, a, b])

def XYZ_to_xyY(XYZ,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE XYZ* tristimulus values to *CIE xyY* colourspace and
    reference *illuminant*.

    Parameters
    ----------
    XYZ : array_like
        *CIE XYZ* tristimulus values.
    illuminant : array_like, optional
        Reference *illuminant* chromaticity coordinates.

    Returns
    -------
    ndarray
        *CIE xyY* colourspace array.

    Notes
    -----
    -   Input *CIE XYZ* tristimulus values are in domain [0, 1].
    -   Output *CIE xyY* colourspace array is in range [0, 1].

    References
    ----------
    .. [2]  Lindbloom, B. (2003). XYZ to xyY. Retrieved February 24, 2014,
            from http://www.brucelindbloom.com/Eqn_XYZ_to_xyY.html

    Examples
    --------
    >>> XYZ = np.array([0.07049534, 0.10080000, 0.09558313])
    >>> XYZ_to_xyY(XYZ)  # doctest: +ELLIPSIS
    array([ 0.2641477...,  0.3777000...,  0.1008    ])
    """

    XYZ = np.asarray(XYZ)
    X, Y, Z = tsplit(XYZ)
    xy_w = np.asarray(illuminant)

    XYZ_n = np.zeros(XYZ.shape)
    XYZ_n[..., 0:2] = xy_w

    xyY = np.where(
        np.all(XYZ == 0, axis=-1)[..., np.newaxis],
        XYZ_n,
        tstack((X / (X + Y + Z), Y / (X + Y + Z), Y)))

    return xyY

def XYZ_to_Luv(XYZ,
               illuminant=ILLUMINANTS.get(
                   'CIE 1931 2 Degree Standard Observer').get('D50')):
    """
    Converts from *CIE XYZ* colourspace to *CIE Luv* colourspace.

    Parameters
    ----------
    XYZ : array_like, (3,)
        *CIE XYZ* colourspace matrix.
    illuminant : array_like, optional
        Reference *illuminant* chromaticity coordinates.

    Returns
    -------
    ndarray, (3,)
        *CIE Luv* colourspace matrix.

    Notes
    -----
    -   Input *CIE XYZ* colourspace matrix is in domain [0, 1].
    -   Input *illuminant* chromaticity coordinates are in domain [0, 1].
    -   Output :math:`L^*` is in domain [0, 100].

    References
    ----------
    .. [2]  Lindbloom, B. (2003). XYZ to Luv. Retrieved February 24, 2014,
            from http://brucelindbloom.com/Eqn_XYZ_to_Luv.html

    Examples
    --------
    >>> XYZ = np.array([0.07049534, 0.1008, 0.09558313])
    >>> XYZ_to_Luv(XYZ)  # doctest: +ELLIPSIS
    array([ 37.9856291..., -28.7922944...,  -1.3558195...])
    """

    X, Y, Z = np.ravel(XYZ)
    Xr, Yr, Zr = np.ravel(xy_to_XYZ(illuminant))

    yr = Y / Yr

    L = 116 * yr ** (1 / 3) - 16 if yr > CIE_E else CIE_K * yr
    u = (13 * L * ((4 * X / (X + 15 * Y + 3 * Z)) -
                   (4 * Xr / (Xr + 15 * Yr + 3 * Zr))))
    v = (13 * L * ((9 * Y / (X + 15 * Y + 3 * Z)) -
                   (9 * Yr / (Xr + 15 * Yr + 3 * Zr))))

    return np.array([L, u, v])