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primaries.py
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primaries.py
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from coords import xy
import whites
import mpmath
class Primaries:
'''
A set of primary colors (red, green, blue) and a white point for an RGB based color space.
'''
def __init__(self, R: xy, G: xy, B: xy, W: xy):
self.R = R
self.G = G
self.B = B
self.W = W
# https://j.mp/TB-2014-004
# https://acescentral.com/aces-documentation/
ACES2065_1 = Primaries(
R=xy('0.73470', '0.26530'),
G=xy('0.00000', '1.00000'),
B=xy('0.00010', '-0.07700'),
W=whites.ACES,
)
# https://j.mp/S-2014-004
# https://acescentral.com/aces-documentation/
ACEScg = Primaries(
R=xy('0.713', '0.293'),
G=xy('0.165', '0.830'),
B=xy('0.128', '0.044'),
W=whites.ACES,
)
# https://www.itu.int/rec/R-REC-BT.2020/en
BT_2020 = Primaries(
R=xy('0.708', '0.292'),
G=xy('0.170', '0.797'),
B=xy('0.131', '0.046'),
W=whites.D65,
)
# https://www.color.org/chardata/rgb/DCIP3.xalter
DCI_P3 = Primaries(
R=xy('0.680', '0.320'),
G=xy('0.265', '0.690'),
B=xy('0.150', '0.060'),
W=whites.DCI,
)
# https://www.color.org/chardata/rgb/DCIP3.xalter
DisplayP3 = Primaries(
R=xy('0.680', '0.320'),
G=xy('0.265', '0.690'),
B=xy('0.150', '0.060'),
W=whites.D65,
)
# https://www.color.org/chardata/rgb/sRGB.xalter
sRGB = Primaries(
R=xy('0.64', '0.33'),
G=xy('0.30', '0.60'),
B=xy('0.15', '0.06'),
W=whites.D65,
)
# http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
def RGB_to_XYZ(rgb: Primaries) -> mpmath.matrix:
'''
Convert linear RGB to chromatic-adapted XYZ
import primaries
M = primaries.RGB_to_XYZ(primaries.sRGB)
XYZ_D65 = M * sRGB_linear
'''
R_XYZ = rgb.R.to_XYZ()
G_XYZ = rgb.G.to_XYZ()
B_XYZ = rgb.B.to_XYZ()
W_XYZ = rgb.W.to_XYZ()
S = mpmath.inverse(mpmath.matrix([
[R_XYZ.X, G_XYZ.X, B_XYZ.X],
[R_XYZ.Y, G_XYZ.Y, B_XYZ.Y],
[R_XYZ.Z, G_XYZ.Z, B_XYZ.Z],
])) * W_XYZ.to_matrix()
M = mpmath.matrix([
[S[0] * R_XYZ.X, S[1] * G_XYZ.X, S[2] * B_XYZ.X],
[S[0] * R_XYZ.Y, S[1] * G_XYZ.Y, S[2] * B_XYZ.Y],
[S[0] * R_XYZ.Z, S[1] * G_XYZ.Z, S[2] * B_XYZ.Z],
])
return M
def RGB_to_RGB(from_rgb: Primaries, to_rgb: Primaries) -> mpmath.matrix:
'''
Convert one linear RGB to another linear RGB
import primaries
M = primaries.RGB_to_RGB(primaries.sRGB, primaries.BT_2020)
BT_2020_linear = M * sRGB_linear
'''
M_1 = RGB_to_XYZ(from_rgb)
if from_rgb.W != to_rgb.W:
M_A = whites.chromatic_adaptation(from_rgb.W, to_rgb.W)
else:
M_A = 1
M_2 = XYZ_to_RGB(to_rgb)
return M_2 * M_A * M_1
def XYZ_to_RGB(rgb: Primaries) -> mpmath.matrix:
'''
Convert chromatic-adapted XYZ to linear RGB
import primaries
M_inv = primaries.XYZ_to_RGB(primaries.sRGB)
sRGB_linear = M_inv * XYZ_D65
'''
return mpmath.inverse(RGB_to_XYZ(rgb))