"""
CMYK Colour Transformations
===========================
Defines various Cyan-Magenta-Yellow (Black) (CMY(K)) colour transformations:
- :func:`colour.RGB_to_CMY`
- :func:`colour.CMY_to_RGB`
- :func:`colour.CMY_to_CMYK`
- :func:`colour.CMYK_to_CMY`
References
----------
- :cite:`EasyRGBh` : EasyRGB. (n.d.). RGB --> CMY. Retrieved May 18, 2014,
from http://www.easyrgb.com/index.php?X=MATH&H=11#text11
- :cite:`EasyRGBi` : EasyRGB. (n.d.). CMY --> RGB. Retrieved May 18, 2014,
from http://www.easyrgb.com/index.php?X=MATH&H=12#text12
- :cite:`EasyRGBm` : EasyRGB. (n.d.). CMYK --> CMY. Retrieved May 18, 2014,
from http://www.easyrgb.com/index.php?X=MATH&H=14#text14
- :cite:`EasyRGBo` : EasyRGB. (n.d.). CMY --> CMYK. Retrieved May 18, 2014,
from http://www.easyrgb.com/index.php?X=MATH&H=13#text13
"""
from __future__ import annotations
import numpy as np
from colour.hints import ArrayLike, NDArray
from colour.utilities import (
as_float_array,
from_range_1,
to_domain_1,
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__ = [
"RGB_to_CMY",
"CMY_to_RGB",
"CMY_to_CMYK",
"CMYK_to_CMY",
]
[docs]def RGB_to_CMY(RGB: ArrayLike) -> NDArray:
"""
Convert from *RGB* colourspace to *CMY* colourspace.
Parameters
----------
RGB
*RGB* colourspace array.
Returns
-------
:class:`numpy.ndarray`
*CMY* array.
Notes
-----
+------------+-----------------------+---------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``RGB`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``CMY`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
References
----------
:cite:`EasyRGBh`
Examples
--------
>>> RGB = np.array([0.45620519, 0.03081071, 0.04091952])
>>> RGB_to_CMY(RGB) # doctest: +ELLIPSIS
array([ 0.5437948..., 0.9691892..., 0.9590804...])
"""
CMY = 1 - to_domain_1(RGB)
return from_range_1(CMY)
[docs]def CMY_to_RGB(CMY: ArrayLike) -> NDArray:
"""
Convert from *CMY* colourspace to *CMY* colourspace.
Parameters
----------
CMY
*CMY* colourspace array.
Returns
-------
:class:`numpy.ndarray`
*RGB* colourspace array.
Notes
-----
+------------+-----------------------+---------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``CMY`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``RGB`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
References
----------
:cite:`EasyRGBi`
Examples
--------
>>> CMY = np.array([0.54379481, 0.96918929, 0.95908048])
>>> CMY_to_RGB(CMY) # doctest: +ELLIPSIS
array([ 0.4562051..., 0.0308107..., 0.0409195...])
"""
RGB = 1 - to_domain_1(CMY)
return from_range_1(RGB)
[docs]def CMY_to_CMYK(CMY: ArrayLike) -> NDArray:
"""
Convert from *CMY* colourspace to *CMYK* colourspace.
Parameters
----------
CMY
*CMY* colourspace array.
Returns
-------
:class:`numpy.ndarray`
*CMYK* array.
Notes
-----
+------------+-----------------------+---------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``CMY`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``CMYK`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
References
----------
:cite:`EasyRGBo`
Examples
--------
>>> CMY = np.array([0.54379481, 0.96918929, 0.95908048])
>>> CMY_to_CMYK(CMY) # doctest: +ELLIPSIS
array([ 0. , 0.9324630..., 0.9103045..., 0.5437948...])
"""
C, M, Y = tsplit(to_domain_1(CMY))
K = np.where(C < 1, C, 1)
K = np.where(M < K, M, K)
K = np.where(Y < K, Y, K)
C = as_float_array((C - K) / (1 - K))
M = as_float_array((M - K) / (1 - K))
Y = as_float_array((Y - K) / (1 - K))
C[np.asarray(K == 1)] = 0
M[np.asarray(K == 1)] = 0
Y[np.asarray(K == 1)] = 0
CMYK = tstack([C, M, Y, K])
return from_range_1(CMYK)
[docs]def CMYK_to_CMY(CMYK: ArrayLike) -> NDArray:
"""
Convert from *CMYK* colourspace to *CMY* colourspace.
Parameters
----------
CMYK
*CMYK* colourspace array.
Returns
-------
:class:`numpy.ndarray`
*CMY* array.
Notes
-----
+------------+-----------------------+---------------+
| **Domain** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``CMYK`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
+------------+-----------------------+---------------+
| **Range** | **Scale - Reference** | **Scale - 1** |
+============+=======================+===============+
| ``CMY`` | [0, 1] | [0, 1] |
+------------+-----------------------+---------------+
References
----------
:cite:`EasyRGBm`
Examples
--------
>>> CMYK = np.array([0.50000000, 0.00000000, 0.74400000, 0.01960784])
>>> CMYK_to_CMY(CMYK) # doctest: +ELLIPSIS
array([ 0.5098039..., 0.0196078..., 0.7490196...])
"""
C, M, Y, K = tsplit(to_domain_1(CMYK))
CMY = tstack([C * (1 - K) + K, M * (1 - K) + K, Y * (1 - K) + K])
return from_range_1(CMY)